734 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
		
		
			
		
	
	
			734 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
|  | <p align="center"> | ||
|  |     <img alt="qs" src="./logos/banner_default.png" width="800" /> | ||
|  | </p> | ||
|  | 
 | ||
|  | # qs <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
 | ||
|  | 
 | ||
|  | [![github actions][actions-image]][actions-url] | ||
|  | [![coverage][codecov-image]][codecov-url] | ||
|  | [![License][license-image]][license-url] | ||
|  | [![Downloads][downloads-image]][downloads-url] | ||
|  | [](https://bestpractices.coreinfrastructure.org/projects/9058) | ||
|  | 
 | ||
|  | [![npm badge][npm-badge-png]][package-url] | ||
|  | 
 | ||
|  | A querystring parsing and stringifying library with some added security. | ||
|  | 
 | ||
|  | Lead Maintainer: [Jordan Harband](https://github.com/ljharb) | ||
|  | 
 | ||
|  | The **qs** module was originally created and maintained by [TJ Holowaychuk](https://github.com/visionmedia/node-querystring). | ||
|  | 
 | ||
|  | ## Usage
 | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var qs = require('qs'); | ||
|  | var assert = require('assert'); | ||
|  | 
 | ||
|  | var obj = qs.parse('a=c'); | ||
|  | assert.deepEqual(obj, { a: 'c' }); | ||
|  | 
 | ||
|  | var str = qs.stringify(obj); | ||
|  | assert.equal(str, 'a=c'); | ||
|  | ``` | ||
|  | 
 | ||
|  | ### Parsing Objects
 | ||
|  | 
 | ||
|  | [](#preventEval) | ||
|  | ```javascript | ||
|  | qs.parse(string, [options]); | ||
|  | ``` | ||
|  | 
 | ||
|  | **qs** allows you to create nested objects within your query strings, by surrounding the name of sub-keys with square brackets `[]`. | ||
|  | For example, the string `'foo[bar]=baz'` converts to: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.deepEqual(qs.parse('foo[bar]=baz'), { | ||
|  |     foo: { | ||
|  |         bar: 'baz' | ||
|  |     } | ||
|  | }); | ||
|  | ``` | ||
|  | 
 | ||
|  | When using the `plainObjects` option the parsed value is returned as a null object, created via `{ __proto__: null }` and as such you should be aware that prototype methods will not exist on it and a user may set those names to whatever value they like: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var nullObject = qs.parse('a[hasOwnProperty]=b', { plainObjects: true }); | ||
|  | assert.deepEqual(nullObject, { a: { hasOwnProperty: 'b' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | By default parameters that would overwrite properties on the object prototype are ignored, if you wish to keep the data from those fields either use `plainObjects` as mentioned above, or set `allowPrototypes` to `true` which will allow user input to overwrite those properties. | ||
|  | *WARNING* It is generally a bad idea to enable this option as it can cause problems when attempting to use the properties that have been overwritten. | ||
|  | Always be careful with this option. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var protoObject = qs.parse('a[hasOwnProperty]=b', { allowPrototypes: true }); | ||
|  | assert.deepEqual(protoObject, { a: { hasOwnProperty: 'b' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | URI encoded strings work too: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.deepEqual(qs.parse('a%5Bb%5D=c'), { | ||
|  |     a: { b: 'c' } | ||
|  | }); | ||
|  | ``` | ||
|  | 
 | ||
|  | You can also nest your objects, like `'foo[bar][baz]=foobarbaz'`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.deepEqual(qs.parse('foo[bar][baz]=foobarbaz'), { | ||
|  |     foo: { | ||
|  |         bar: { | ||
|  |             baz: 'foobarbaz' | ||
|  |         } | ||
|  |     } | ||
|  | }); | ||
|  | ``` | ||
|  | 
 | ||
|  | By default, when nesting objects **qs** will only parse up to 5 children deep. | ||
|  | This means if you attempt to parse a string like `'a[b][c][d][e][f][g][h][i]=j'` your resulting object will be: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var expected = { | ||
|  |     a: { | ||
|  |         b: { | ||
|  |             c: { | ||
|  |                 d: { | ||
|  |                     e: { | ||
|  |                         f: { | ||
|  |                             '[g][h][i]': 'j' | ||
|  |                         } | ||
|  |                     } | ||
|  |                 } | ||
|  |             } | ||
|  |         } | ||
|  |     } | ||
|  | }; | ||
|  | var string = 'a[b][c][d][e][f][g][h][i]=j'; | ||
|  | assert.deepEqual(qs.parse(string), expected); | ||
|  | ``` | ||
|  | 
 | ||
|  | This depth can be overridden by passing a `depth` option to `qs.parse(string, [options])`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var deep = qs.parse('a[b][c][d][e][f][g][h][i]=j', { depth: 1 }); | ||
|  | assert.deepEqual(deep, { a: { b: { '[c][d][e][f][g][h][i]': 'j' } } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | You can configure **qs** to throw an error when parsing nested input beyond this depth using the `strictDepth` option (defaulted to false): | ||
|  | 
 | ||
|  | ```javascript | ||
|  | try { | ||
|  |     qs.parse('a[b][c][d][e][f][g][h][i]=j', { depth: 1, strictDepth: true }); | ||
|  | } catch (err) { | ||
|  |     assert(err instanceof RangeError); | ||
|  |     assert.strictEqual(err.message, 'Input depth exceeded depth option of 1 and strictDepth is true'); | ||
|  | } | ||
|  | ``` | ||
|  | 
 | ||
|  | The depth limit helps mitigate abuse when **qs** is used to parse user input, and it is recommended to keep it a reasonably small number. The strictDepth option adds a layer of protection by throwing an error when the limit is exceeded, allowing you to catch and handle such cases. | ||
|  | 
 | ||
|  | For similar reasons, by default **qs** will only parse up to 1000 parameters. This can be overridden by passing a `parameterLimit` option: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var limited = qs.parse('a=b&c=d', { parameterLimit: 1 }); | ||
|  | assert.deepEqual(limited, { a: 'b' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you want an error to be thrown whenever the a limit is exceeded (eg, `parameterLimit`, `arrayLimit`), set the `throwOnLimitExceeded` option to `true`. This option will generate a descriptive error if the query string exceeds a configured limit. | ||
|  | ```javascript | ||
|  | try { | ||
|  |     qs.parse('a=1&b=2&c=3&d=4', { parameterLimit: 3, throwOnLimitExceeded: true }); | ||
|  | } catch (err) { | ||
|  |     assert(err instanceof Error); | ||
|  |     assert.strictEqual(err.message, 'Parameter limit exceeded. Only 3 parameters allowed.'); | ||
|  | } | ||
|  | ``` | ||
|  | 
 | ||
|  | When `throwOnLimitExceeded` is set to `false` (default), **qs** will parse up to the specified `parameterLimit` and ignore the rest without throwing an error. | ||
|  | 
 | ||
|  | To bypass the leading question mark, use `ignoreQueryPrefix`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var prefixed = qs.parse('?a=b&c=d', { ignoreQueryPrefix: true }); | ||
|  | assert.deepEqual(prefixed, { a: 'b', c: 'd' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | An optional delimiter can also be passed: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var delimited = qs.parse('a=b;c=d', { delimiter: ';' }); | ||
|  | assert.deepEqual(delimited, { a: 'b', c: 'd' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Delimiters can be a regular expression too: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var regexed = qs.parse('a=b;c=d,e=f', { delimiter: /[;,]/ }); | ||
|  | assert.deepEqual(regexed, { a: 'b', c: 'd', e: 'f' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Option `allowDots` can be used to enable dot notation: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withDots = qs.parse('a.b=c', { allowDots: true }); | ||
|  | assert.deepEqual(withDots, { a: { b: 'c' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Option `decodeDotInKeys` can be used to decode dots in keys | ||
|  | Note: it implies `allowDots`, so `parse` will error if you set `decodeDotInKeys` to `true`, and `allowDots` to `false`. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withDots = qs.parse('name%252Eobj.first=John&name%252Eobj.last=Doe', { decodeDotInKeys: true }); | ||
|  | assert.deepEqual(withDots, { 'name.obj': { first: 'John', last: 'Doe' }}); | ||
|  | ``` | ||
|  | 
 | ||
|  | Option `allowEmptyArrays` can be used to allowing empty array values in object | ||
|  | ```javascript | ||
|  | var withEmptyArrays = qs.parse('foo[]&bar=baz', { allowEmptyArrays: true }); | ||
|  | assert.deepEqual(withEmptyArrays, { foo: [], bar: 'baz' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Option `duplicates` can be used to change the behavior when duplicate keys are encountered | ||
|  | ```javascript | ||
|  | assert.deepEqual(qs.parse('foo=bar&foo=baz'), { foo: ['bar', 'baz'] }); | ||
|  | assert.deepEqual(qs.parse('foo=bar&foo=baz', { duplicates: 'combine' }), { foo: ['bar', 'baz'] }); | ||
|  | assert.deepEqual(qs.parse('foo=bar&foo=baz', { duplicates: 'first' }), { foo: 'bar' }); | ||
|  | assert.deepEqual(qs.parse('foo=bar&foo=baz', { duplicates: 'last' }), { foo: 'baz' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you have to deal with legacy browsers or services, there's also support for decoding percent-encoded octets as iso-8859-1: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var oldCharset = qs.parse('a=%A7', { charset: 'iso-8859-1' }); | ||
|  | assert.deepEqual(oldCharset, { a: '§' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Some services add an initial `utf8=✓` value to forms so that old Internet Explorer versions are more likely to submit the form as utf-8. | ||
|  | Additionally, the server can check the value against wrong encodings of the checkmark character and detect that a query string or `application/x-www-form-urlencoded` body was *not* sent as utf-8, eg. if the form had an `accept-charset` parameter or the containing page had a different character set. | ||
|  | 
 | ||
|  | **qs** supports this mechanism via the `charsetSentinel` option. | ||
|  | If specified, the `utf8` parameter will be omitted from the returned object. | ||
|  | It will be used to switch to `iso-8859-1`/`utf-8` mode depending on how the checkmark is encoded. | ||
|  | 
 | ||
|  | **Important**: When you specify both the `charset` option and the `charsetSentinel` option, the `charset` will be overridden when the request contains a `utf8` parameter from which the actual charset can be deduced. | ||
|  | In that sense the `charset` will behave as the default charset rather than the authoritative charset. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var detectedAsUtf8 = qs.parse('utf8=%E2%9C%93&a=%C3%B8', { | ||
|  |     charset: 'iso-8859-1', | ||
|  |     charsetSentinel: true | ||
|  | }); | ||
|  | assert.deepEqual(detectedAsUtf8, { a: 'ø' }); | ||
|  | 
 | ||
|  | // Browsers encode the checkmark as ✓ when submitting as iso-8859-1: | ||
|  | var detectedAsIso8859_1 = qs.parse('utf8=%26%2310003%3B&a=%F8', { | ||
|  |     charset: 'utf-8', | ||
|  |     charsetSentinel: true | ||
|  | }); | ||
|  | assert.deepEqual(detectedAsIso8859_1, { a: 'ø' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you want to decode the `&#...;` syntax to the actual character, you can specify the `interpretNumericEntities` option as well: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var detectedAsIso8859_1 = qs.parse('a=%26%239786%3B', { | ||
|  |     charset: 'iso-8859-1', | ||
|  |     interpretNumericEntities: true | ||
|  | }); | ||
|  | assert.deepEqual(detectedAsIso8859_1, { a: '☺' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | It also works when the charset has been detected in `charsetSentinel` mode. | ||
|  | 
 | ||
|  | ### Parsing Arrays
 | ||
|  | 
 | ||
|  | **qs** can also parse arrays using a similar `[]` notation: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withArray = qs.parse('a[]=b&a[]=c'); | ||
|  | assert.deepEqual(withArray, { a: ['b', 'c'] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | You may specify an index as well: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withIndexes = qs.parse('a[1]=c&a[0]=b'); | ||
|  | assert.deepEqual(withIndexes, { a: ['b', 'c'] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Note that the only difference between an index in an array and a key in an object is that the value between the brackets must be a number to create an array. | ||
|  | When creating arrays with specific indices, **qs** will compact a sparse array to only the existing values preserving their order: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var noSparse = qs.parse('a[1]=b&a[15]=c'); | ||
|  | assert.deepEqual(noSparse, { a: ['b', 'c'] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | You may also use `allowSparse` option to parse sparse arrays: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var sparseArray = qs.parse('a[1]=2&a[3]=5', { allowSparse: true }); | ||
|  | assert.deepEqual(sparseArray, { a: [, '2', , '5'] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Note that an empty string is also a value, and will be preserved: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withEmptyString = qs.parse('a[]=&a[]=b'); | ||
|  | assert.deepEqual(withEmptyString, { a: ['', 'b'] }); | ||
|  | 
 | ||
|  | var withIndexedEmptyString = qs.parse('a[0]=b&a[1]=&a[2]=c'); | ||
|  | assert.deepEqual(withIndexedEmptyString, { a: ['b', '', 'c'] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | **qs** will also limit specifying indices in an array to a maximum index of `20`. | ||
|  | Any array members with an index of greater than `20` will instead be converted to an object with the index as the key. | ||
|  | This is needed to handle cases when someone sent, for example, `a[999999999]` and it will take significant time to iterate over this huge array. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withMaxIndex = qs.parse('a[100]=b'); | ||
|  | assert.deepEqual(withMaxIndex, { a: { '100': 'b' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | This limit can be overridden by passing an `arrayLimit` option: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withArrayLimit = qs.parse('a[1]=b', { arrayLimit: 0 }); | ||
|  | assert.deepEqual(withArrayLimit, { a: { '1': 'b' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you want to throw an error whenever the array limit is exceeded, set the `throwOnLimitExceeded` option to `true`. This option will generate a descriptive error if the query string exceeds a configured limit. | ||
|  | ```javascript | ||
|  | try { | ||
|  |     qs.parse('a[1]=b', { arrayLimit: 0, throwOnLimitExceeded: true }); | ||
|  | } catch (err) { | ||
|  |     assert(err instanceof Error); | ||
|  |     assert.strictEqual(err.message, 'Array limit exceeded. Only 0 elements allowed in an array.'); | ||
|  | } | ||
|  | ``` | ||
|  | 
 | ||
|  | When `throwOnLimitExceeded` is set to `false` (default), **qs** will parse up to the specified `arrayLimit` and if the limit is exceeded, the array will instead be converted to an object with the index as the key | ||
|  | 
 | ||
|  | To disable array parsing entirely, set `parseArrays` to `false`. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var noParsingArrays = qs.parse('a[]=b', { parseArrays: false }); | ||
|  | assert.deepEqual(noParsingArrays, { a: { '0': 'b' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you mix notations, **qs** will merge the two items into an object: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var mixedNotation = qs.parse('a[0]=b&a[b]=c'); | ||
|  | assert.deepEqual(mixedNotation, { a: { '0': 'b', b: 'c' } }); | ||
|  | ``` | ||
|  | 
 | ||
|  | You can also create arrays of objects: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var arraysOfObjects = qs.parse('a[][b]=c'); | ||
|  | assert.deepEqual(arraysOfObjects, { a: [{ b: 'c' }] }); | ||
|  | ``` | ||
|  | 
 | ||
|  | Some people use comma to join array, **qs** can parse it: | ||
|  | ```javascript | ||
|  | var arraysOfObjects = qs.parse('a=b,c', { comma: true }) | ||
|  | assert.deepEqual(arraysOfObjects, { a: ['b', 'c'] }) | ||
|  | ``` | ||
|  | (_this cannot convert nested objects, such as `a={b:1},{c:d}`_) | ||
|  | 
 | ||
|  | ### Parsing primitive/scalar values (numbers, booleans, null, etc)
 | ||
|  | 
 | ||
|  | By default, all values are parsed as strings. | ||
|  | This behavior will not change and is explained in [issue #91](https://github.com/ljharb/qs/issues/91). | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var primitiveValues = qs.parse('a=15&b=true&c=null'); | ||
|  | assert.deepEqual(primitiveValues, { a: '15', b: 'true', c: 'null' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you wish to auto-convert values which look like numbers, booleans, and other values into their primitive counterparts, you can use the [query-types Express JS middleware](https://github.com/xpepermint/query-types) which will auto-convert all request query parameters. | ||
|  | 
 | ||
|  | ### Stringifying
 | ||
|  | 
 | ||
|  | [](#preventEval) | ||
|  | ```javascript | ||
|  | qs.stringify(object, [options]); | ||
|  | ``` | ||
|  | 
 | ||
|  | When stringifying, **qs** by default URI encodes output. Objects are stringified as you would expect: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: 'b' }), 'a=b'); | ||
|  | assert.equal(qs.stringify({ a: { b: 'c' } }), 'a%5Bb%5D=c'); | ||
|  | ``` | ||
|  | 
 | ||
|  | This encoding can be disabled by setting the `encode` option to `false`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var unencoded = qs.stringify({ a: { b: 'c' } }, { encode: false }); | ||
|  | assert.equal(unencoded, 'a[b]=c'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Encoding can be disabled for keys by setting the `encodeValuesOnly` option to `true`: | ||
|  | ```javascript | ||
|  | var encodedValues = qs.stringify( | ||
|  |     { a: 'b', c: ['d', 'e=f'], f: [['g'], ['h']] }, | ||
|  |     { encodeValuesOnly: true } | ||
|  | ); | ||
|  | assert.equal(encodedValues,'a=b&c[0]=d&c[1]=e%3Df&f[0][0]=g&f[1][0]=h'); | ||
|  | ``` | ||
|  | 
 | ||
|  | This encoding can also be replaced by a custom encoding method set as `encoder` option: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var encoded = qs.stringify({ a: { b: 'c' } }, { encoder: function (str) { | ||
|  |     // Passed in values `a`, `b`, `c` | ||
|  |     return // Return encoded string | ||
|  | }}) | ||
|  | ``` | ||
|  | 
 | ||
|  | _(Note: the `encoder` option does not apply if `encode` is `false`)_ | ||
|  | 
 | ||
|  | Analogue to the `encoder` there is a `decoder` option for `parse` to override decoding of properties and values: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var decoded = qs.parse('x=z', { decoder: function (str) { | ||
|  |     // Passed in values `x`, `z` | ||
|  |     return // Return decoded string | ||
|  | }}) | ||
|  | ``` | ||
|  | 
 | ||
|  | You can encode keys and values using different logic by using the type argument provided to the encoder: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var encoded = qs.stringify({ a: { b: 'c' } }, { encoder: function (str, defaultEncoder, charset, type) { | ||
|  |     if (type === 'key') { | ||
|  |         return // Encoded key | ||
|  |     } else if (type === 'value') { | ||
|  |         return // Encoded value | ||
|  |     } | ||
|  | }}) | ||
|  | ``` | ||
|  | 
 | ||
|  | The type argument is also provided to the decoder: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var decoded = qs.parse('x=z', { decoder: function (str, defaultDecoder, charset, type) { | ||
|  |     if (type === 'key') { | ||
|  |         return // Decoded key | ||
|  |     } else if (type === 'value') { | ||
|  |         return // Decoded value | ||
|  |     } | ||
|  | }}) | ||
|  | ``` | ||
|  | 
 | ||
|  | Examples beyond this point will be shown as though the output is not URI encoded for clarity. | ||
|  | Please note that the return values in these cases *will* be URI encoded during real usage. | ||
|  | 
 | ||
|  | When arrays are stringified, they follow the `arrayFormat` option, which defaults to `indices`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify({ a: ['b', 'c', 'd'] }); | ||
|  | // 'a[0]=b&a[1]=c&a[2]=d' | ||
|  | ``` | ||
|  | 
 | ||
|  | You may override this by setting the `indices` option to `false`, or to be more explicit, the `arrayFormat` option to `repeat`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify({ a: ['b', 'c', 'd'] }, { indices: false }); | ||
|  | // 'a=b&a=c&a=d' | ||
|  | ``` | ||
|  | 
 | ||
|  | You may use the `arrayFormat` option to specify the format of the output array: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'indices' }) | ||
|  | // 'a[0]=b&a[1]=c' | ||
|  | qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' }) | ||
|  | // 'a[]=b&a[]=c' | ||
|  | qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' }) | ||
|  | // 'a=b&a=c' | ||
|  | qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'comma' }) | ||
|  | // 'a=b,c' | ||
|  | ``` | ||
|  | 
 | ||
|  | Note: when using `arrayFormat` set to `'comma'`, you can also pass the `commaRoundTrip` option set to `true` or `false`, to append `[]` on single-item arrays, so that they can round trip through a parse. | ||
|  | 
 | ||
|  | When objects are stringified, by default they use bracket notation: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify({ a: { b: { c: 'd', e: 'f' } } }); | ||
|  | // 'a[b][c]=d&a[b][e]=f' | ||
|  | ``` | ||
|  | 
 | ||
|  | You may override this to use dot notation by setting the `allowDots` option to `true`: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify({ a: { b: { c: 'd', e: 'f' } } }, { allowDots: true }); | ||
|  | // 'a.b.c=d&a.b.e=f' | ||
|  | ``` | ||
|  | 
 | ||
|  | You may encode the dot notation in the keys of object with option `encodeDotInKeys` by setting it to `true`: | ||
|  | Note: it implies `allowDots`, so `stringify` will error if you set `decodeDotInKeys` to `true`, and `allowDots` to `false`. | ||
|  | Caveat: when `encodeValuesOnly` is `true` as well as `encodeDotInKeys`, only dots in keys and nothing else will be encoded. | ||
|  | ```javascript | ||
|  | qs.stringify({ "name.obj": { "first": "John", "last": "Doe" } }, { allowDots: true, encodeDotInKeys: true }) | ||
|  | // 'name%252Eobj.first=John&name%252Eobj.last=Doe' | ||
|  | ``` | ||
|  | 
 | ||
|  | You may allow empty array values by setting the `allowEmptyArrays` option to `true`: | ||
|  | ```javascript | ||
|  | qs.stringify({ foo: [], bar: 'baz' }, { allowEmptyArrays: true }); | ||
|  | // 'foo[]&bar=baz' | ||
|  | ``` | ||
|  | 
 | ||
|  | Empty strings and null values will omit the value, but the equals sign (=) remains in place: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: '' }), 'a='); | ||
|  | ``` | ||
|  | 
 | ||
|  | Key with no values (such as an empty object or array) will return nothing: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: [] }), ''); | ||
|  | assert.equal(qs.stringify({ a: {} }), ''); | ||
|  | assert.equal(qs.stringify({ a: [{}] }), ''); | ||
|  | assert.equal(qs.stringify({ a: { b: []} }), ''); | ||
|  | assert.equal(qs.stringify({ a: { b: {}} }), ''); | ||
|  | ``` | ||
|  | 
 | ||
|  | Properties that are set to `undefined` will be omitted entirely: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: null, b: undefined }), 'a='); | ||
|  | ``` | ||
|  | 
 | ||
|  | The query string may optionally be prepended with a question mark: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: 'b', c: 'd' }, { addQueryPrefix: true }), '?a=b&c=d'); | ||
|  | ``` | ||
|  | 
 | ||
|  | The delimiter may be overridden with stringify as well: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | assert.equal(qs.stringify({ a: 'b', c: 'd' }, { delimiter: ';' }), 'a=b;c=d'); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you only want to override the serialization of `Date` objects, you can provide a `serializeDate` option: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var date = new Date(7); | ||
|  | assert.equal(qs.stringify({ a: date }), 'a=1970-01-01T00:00:00.007Z'.replace(/:/g, '%3A')); | ||
|  | assert.equal( | ||
|  |     qs.stringify({ a: date }, { serializeDate: function (d) { return d.getTime(); } }), | ||
|  |     'a=7' | ||
|  | ); | ||
|  | ``` | ||
|  | 
 | ||
|  | You may use the `sort` option to affect the order of parameter keys: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | function alphabeticalSort(a, b) { | ||
|  |     return a.localeCompare(b); | ||
|  | } | ||
|  | assert.equal(qs.stringify({ a: 'c', z: 'y', b : 'f' }, { sort: alphabeticalSort }), 'a=c&b=f&z=y'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Finally, you can use the `filter` option to restrict which keys will be included in the stringified output. | ||
|  | If you pass a function, it will be called for each key to obtain the replacement value. | ||
|  | Otherwise, if you pass an array, it will be used to select properties and array indices for stringification: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | function filterFunc(prefix, value) { | ||
|  |     if (prefix == 'b') { | ||
|  |         // Return an `undefined` value to omit a property. | ||
|  |         return; | ||
|  |     } | ||
|  |     if (prefix == 'e[f]') { | ||
|  |         return value.getTime(); | ||
|  |     } | ||
|  |     if (prefix == 'e[g][0]') { | ||
|  |         return value * 2; | ||
|  |     } | ||
|  |     return value; | ||
|  | } | ||
|  | qs.stringify({ a: 'b', c: 'd', e: { f: new Date(123), g: [2] } }, { filter: filterFunc }); | ||
|  | // 'a=b&c=d&e[f]=123&e[g][0]=4' | ||
|  | qs.stringify({ a: 'b', c: 'd', e: 'f' }, { filter: ['a', 'e'] }); | ||
|  | // 'a=b&e=f' | ||
|  | qs.stringify({ a: ['b', 'c', 'd'], e: 'f' }, { filter: ['a', 0, 2] }); | ||
|  | // 'a[0]=b&a[2]=d' | ||
|  | ``` | ||
|  | 
 | ||
|  | You could also use `filter` to inject custom serialization for user defined types. | ||
|  | Consider you're working with some api that expects query strings of the format for ranges: | ||
|  | 
 | ||
|  | ``` | ||
|  | https://domain.com/endpoint?range=30...70 | ||
|  | ``` | ||
|  | 
 | ||
|  | For which you model as: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | class Range { | ||
|  |     constructor(from, to) { | ||
|  |         this.from = from; | ||
|  |         this.to = to; | ||
|  |     } | ||
|  | } | ||
|  | ``` | ||
|  | 
 | ||
|  | You could _inject_ a custom serializer to handle values of this type: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | qs.stringify( | ||
|  |     { | ||
|  |         range: new Range(30, 70), | ||
|  |     }, | ||
|  |     { | ||
|  |         filter: (prefix, value) => { | ||
|  |             if (value instanceof Range) { | ||
|  |                 return `${value.from}...${value.to}`; | ||
|  |             } | ||
|  |             // serialize the usual way | ||
|  |             return value; | ||
|  |         }, | ||
|  |     } | ||
|  | ); | ||
|  | // range=30...70 | ||
|  | ``` | ||
|  | 
 | ||
|  | ### Handling of `null` values
 | ||
|  | 
 | ||
|  | By default, `null` values are treated like empty strings: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var withNull = qs.stringify({ a: null, b: '' }); | ||
|  | assert.equal(withNull, 'a=&b='); | ||
|  | ``` | ||
|  | 
 | ||
|  | Parsing does not distinguish between parameters with and without equal signs. | ||
|  | Both are converted to empty strings. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var equalsInsensitive = qs.parse('a&b='); | ||
|  | assert.deepEqual(equalsInsensitive, { a: '', b: '' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | To distinguish between `null` values and empty strings use the `strictNullHandling` flag. In the result string the `null` | ||
|  | values have no `=` sign: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var strictNull = qs.stringify({ a: null, b: '' }, { strictNullHandling: true }); | ||
|  | assert.equal(strictNull, 'a&b='); | ||
|  | ``` | ||
|  | 
 | ||
|  | To parse values without `=` back to `null` use the `strictNullHandling` flag: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var parsedStrictNull = qs.parse('a&b=', { strictNullHandling: true }); | ||
|  | assert.deepEqual(parsedStrictNull, { a: null, b: '' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | To completely skip rendering keys with `null` values, use the `skipNulls` flag: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var nullsSkipped = qs.stringify({ a: 'b', c: null}, { skipNulls: true }); | ||
|  | assert.equal(nullsSkipped, 'a=b'); | ||
|  | ``` | ||
|  | 
 | ||
|  | If you're communicating with legacy systems, you can switch to `iso-8859-1` using the `charset` option: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var iso = qs.stringify({ æ: 'æ' }, { charset: 'iso-8859-1' }); | ||
|  | assert.equal(iso, '%E6=%E6'); | ||
|  | ``` | ||
|  | 
 | ||
|  | Characters that don't exist in `iso-8859-1` will be converted to numeric entities, similar to what browsers do: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var numeric = qs.stringify({ a: '☺' }, { charset: 'iso-8859-1' }); | ||
|  | assert.equal(numeric, 'a=%26%239786%3B'); | ||
|  | ``` | ||
|  | 
 | ||
|  | You can use the `charsetSentinel` option to announce the character by including an `utf8=✓` parameter with the proper encoding if the checkmark, similar to what Ruby on Rails and others do when submitting forms. | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var sentinel = qs.stringify({ a: '☺' }, { charsetSentinel: true }); | ||
|  | assert.equal(sentinel, 'utf8=%E2%9C%93&a=%E2%98%BA'); | ||
|  | 
 | ||
|  | var isoSentinel = qs.stringify({ a: 'æ' }, { charsetSentinel: true, charset: 'iso-8859-1' }); | ||
|  | assert.equal(isoSentinel, 'utf8=%26%2310003%3B&a=%E6'); | ||
|  | ``` | ||
|  | 
 | ||
|  | ### Dealing with special character sets
 | ||
|  | 
 | ||
|  | By default the encoding and decoding of characters is done in `utf-8`, and `iso-8859-1` support is also built in via the `charset` parameter. | ||
|  | 
 | ||
|  | If you wish to encode querystrings to a different character set (i.e. | ||
|  | [Shift JIS](https://en.wikipedia.org/wiki/Shift_JIS)) you can use the | ||
|  | [`qs-iconv`](https://github.com/martinheidegger/qs-iconv) library: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var encoder = require('qs-iconv/encoder')('shift_jis'); | ||
|  | var shiftJISEncoded = qs.stringify({ a: 'こんにちは!' }, { encoder: encoder }); | ||
|  | assert.equal(shiftJISEncoded, 'a=%82%B1%82%F1%82%C9%82%BF%82%CD%81I'); | ||
|  | ``` | ||
|  | 
 | ||
|  | This also works for decoding of query strings: | ||
|  | 
 | ||
|  | ```javascript | ||
|  | var decoder = require('qs-iconv/decoder')('shift_jis'); | ||
|  | var obj = qs.parse('a=%82%B1%82%F1%82%C9%82%BF%82%CD%81I', { decoder: decoder }); | ||
|  | assert.deepEqual(obj, { a: 'こんにちは!' }); | ||
|  | ``` | ||
|  | 
 | ||
|  | ### RFC 3986 and RFC 1738 space encoding
 | ||
|  | 
 | ||
|  | RFC3986 used as default option and encodes ' ' to *%20* which is backward compatible. | ||
|  | In the same time, output can be stringified as per RFC1738 with ' ' equal to '+'. | ||
|  | 
 | ||
|  | ``` | ||
|  | assert.equal(qs.stringify({ a: 'b c' }), 'a=b%20c'); | ||
|  | assert.equal(qs.stringify({ a: 'b c' }, { format : 'RFC3986' }), 'a=b%20c'); | ||
|  | assert.equal(qs.stringify({ a: 'b c' }, { format : 'RFC1738' }), 'a=b+c'); | ||
|  | ``` | ||
|  | 
 | ||
|  | ## Security
 | ||
|  | 
 | ||
|  | Please email [@ljharb](https://github.com/ljharb) or see https://tidelift.com/security if you have a potential security vulnerability to report. | ||
|  | 
 | ||
|  | ## qs for enterprise
 | ||
|  | 
 | ||
|  | Available as part of the Tidelift Subscription | ||
|  | 
 | ||
|  | The maintainers of qs and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. | ||
|  | Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. | ||
|  | [Learn more.](https://tidelift.com/subscription/pkg/npm-qs?utm_source=npm-qs&utm_medium=referral&utm_campaign=enterprise&utm_term=repo) | ||
|  | 
 | ||
|  | [package-url]: https://npmjs.org/package/qs | ||
|  | [npm-version-svg]: https://versionbadg.es/ljharb/qs.svg | ||
|  | [deps-svg]: https://david-dm.org/ljharb/qs.svg | ||
|  | [deps-url]: https://david-dm.org/ljharb/qs | ||
|  | [dev-deps-svg]: https://david-dm.org/ljharb/qs/dev-status.svg | ||
|  | [dev-deps-url]: https://david-dm.org/ljharb/qs#info=devDependencies | ||
|  | [npm-badge-png]: https://nodei.co/npm/qs.png?downloads=true&stars=true | ||
|  | [license-image]: https://img.shields.io/npm/l/qs.svg | ||
|  | [license-url]: LICENSE | ||
|  | [downloads-image]: https://img.shields.io/npm/dm/qs.svg | ||
|  | [downloads-url]: https://npm-stat.com/charts.html?package=qs | ||
|  | [codecov-image]: https://codecov.io/gh/ljharb/qs/branch/main/graphs/badge.svg | ||
|  | [codecov-url]: https://app.codecov.io/gh/ljharb/qs/ | ||
|  | [actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/ljharb/qs | ||
|  | [actions-url]: https://github.com/ljharb/qs/actions | ||
|  | 
 | ||
|  | ## Acknowledgements
 | ||
|  | 
 | ||
|  | qs logo by [NUMI](https://github.com/numi-hq/open-design): | ||
|  | 
 | ||
|  | [<img src="https://raw.githubusercontent.com/numi-hq/open-design/main/assets/numi-lockup.png" alt="NUMI Logo" style="width: 200px;"/>](https://numi.tech/?ref=qs) |