README.md (18228B)
1 # qs <sup>[![Version Badge][2]][1]</sup> 2 3 [![Build Status][3]][4] 4 [![dependency status][5]][6] 5 [![dev dependency status][7]][8] 6 [![License][license-image]][license-url] 7 [![Downloads][downloads-image]][downloads-url] 8 9 [![npm badge][11]][1] 10 11 A querystring parsing and stringifying library with some added security. 12 13 Lead Maintainer: [Jordan Harband](https://github.com/ljharb) 14 15 The **qs** module was originally created and maintained by [TJ Holowaychuk](https://github.com/visionmedia/node-querystring). 16 17 ## Usage 18 19 ```javascript 20 var qs = require('qs'); 21 var assert = require('assert'); 22 23 var obj = qs.parse('a=c'); 24 assert.deepEqual(obj, { a: 'c' }); 25 26 var str = qs.stringify(obj); 27 assert.equal(str, 'a=c'); 28 ``` 29 30 ### Parsing Objects 31 32 [](#preventEval) 33 ```javascript 34 qs.parse(string, [options]); 35 ``` 36 37 **qs** allows you to create nested objects within your query strings, by surrounding the name of sub-keys with square brackets `[]`. 38 For example, the string `'foo[bar]=baz'` converts to: 39 40 ```javascript 41 assert.deepEqual(qs.parse('foo[bar]=baz'), { 42 foo: { 43 bar: 'baz' 44 } 45 }); 46 ``` 47 48 When using the `plainObjects` option the parsed value is returned as a null object, created via `Object.create(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: 49 50 ```javascript 51 var nullObject = qs.parse('a[hasOwnProperty]=b', { plainObjects: true }); 52 assert.deepEqual(nullObject, { a: { hasOwnProperty: 'b' } }); 53 ``` 54 55 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. 56 57 ```javascript 58 var protoObject = qs.parse('a[hasOwnProperty]=b', { allowPrototypes: true }); 59 assert.deepEqual(protoObject, { a: { hasOwnProperty: 'b' } }); 60 ``` 61 62 URI encoded strings work too: 63 64 ```javascript 65 assert.deepEqual(qs.parse('a%5Bb%5D=c'), { 66 a: { b: 'c' } 67 }); 68 ``` 69 70 You can also nest your objects, like `'foo[bar][baz]=foobarbaz'`: 71 72 ```javascript 73 assert.deepEqual(qs.parse('foo[bar][baz]=foobarbaz'), { 74 foo: { 75 bar: { 76 baz: 'foobarbaz' 77 } 78 } 79 }); 80 ``` 81 82 By default, when nesting objects **qs** will only parse up to 5 children deep. This means if you attempt to parse a string like 83 `'a[b][c][d][e][f][g][h][i]=j'` your resulting object will be: 84 85 ```javascript 86 var expected = { 87 a: { 88 b: { 89 c: { 90 d: { 91 e: { 92 f: { 93 '[g][h][i]': 'j' 94 } 95 } 96 } 97 } 98 } 99 } 100 }; 101 var string = 'a[b][c][d][e][f][g][h][i]=j'; 102 assert.deepEqual(qs.parse(string), expected); 103 ``` 104 105 This depth can be overridden by passing a `depth` option to `qs.parse(string, [options])`: 106 107 ```javascript 108 var deep = qs.parse('a[b][c][d][e][f][g][h][i]=j', { depth: 1 }); 109 assert.deepEqual(deep, { a: { b: { '[c][d][e][f][g][h][i]': 'j' } } }); 110 ``` 111 112 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. 113 114 For similar reasons, by default **qs** will only parse up to 1000 parameters. This can be overridden by passing a `parameterLimit` option: 115 116 ```javascript 117 var limited = qs.parse('a=b&c=d', { parameterLimit: 1 }); 118 assert.deepEqual(limited, { a: 'b' }); 119 ``` 120 121 To bypass the leading question mark, use `ignoreQueryPrefix`: 122 123 ```javascript 124 var prefixed = qs.parse('?a=b&c=d', { ignoreQueryPrefix: true }); 125 assert.deepEqual(prefixed, { a: 'b', c: 'd' }); 126 ``` 127 128 An optional delimiter can also be passed: 129 130 ```javascript 131 var delimited = qs.parse('a=b;c=d', { delimiter: ';' }); 132 assert.deepEqual(delimited, { a: 'b', c: 'd' }); 133 ``` 134 135 Delimiters can be a regular expression too: 136 137 ```javascript 138 var regexed = qs.parse('a=b;c=d,e=f', { delimiter: /[;,]/ }); 139 assert.deepEqual(regexed, { a: 'b', c: 'd', e: 'f' }); 140 ``` 141 142 Option `allowDots` can be used to enable dot notation: 143 144 ```javascript 145 var withDots = qs.parse('a.b=c', { allowDots: true }); 146 assert.deepEqual(withDots, { a: { b: 'c' } }); 147 ``` 148 149 If you have to deal with legacy browsers or services, there's 150 also support for decoding percent-encoded octets as iso-8859-1: 151 152 ```javascript 153 var oldCharset = qs.parse('a=%A7', { charset: 'iso-8859-1' }); 154 assert.deepEqual(oldCharset, { a: '§' }); 155 ``` 156 157 Some services add an initial `utf8=✓` value to forms so that old 158 Internet Explorer versions are more likely to submit the form as 159 utf-8. Additionally, the server can check the value against wrong 160 encodings of the checkmark character and detect that a query string 161 or `application/x-www-form-urlencoded` body was *not* sent as 162 utf-8, eg. if the form had an `accept-charset` parameter or the 163 containing page had a different character set. 164 165 **qs** supports this mechanism via the `charsetSentinel` option. 166 If specified, the `utf8` parameter will be omitted from the 167 returned object. It will be used to switch to `iso-8859-1`/`utf-8` 168 mode depending on how the checkmark is encoded. 169 170 **Important**: When you specify both the `charset` option and the 171 `charsetSentinel` option, the `charset` will be overridden when 172 the request contains a `utf8` parameter from which the actual 173 charset can be deduced. In that sense the `charset` will behave 174 as the default charset rather than the authoritative charset. 175 176 ```javascript 177 var detectedAsUtf8 = qs.parse('utf8=%E2%9C%93&a=%C3%B8', { 178 charset: 'iso-8859-1', 179 charsetSentinel: true 180 }); 181 assert.deepEqual(detectedAsUtf8, { a: 'ø' }); 182 183 // Browsers encode the checkmark as ✓ when submitting as iso-8859-1: 184 var detectedAsIso8859_1 = qs.parse('utf8=%26%2310003%3B&a=%F8', { 185 charset: 'utf-8', 186 charsetSentinel: true 187 }); 188 assert.deepEqual(detectedAsIso8859_1, { a: 'ø' }); 189 ``` 190 191 If you want to decode the `&#...;` syntax to the actual character, 192 you can specify the `interpretNumericEntities` option as well: 193 194 ```javascript 195 var detectedAsIso8859_1 = qs.parse('a=%26%239786%3B', { 196 charset: 'iso-8859-1', 197 interpretNumericEntities: true 198 }); 199 assert.deepEqual(detectedAsIso8859_1, { a: '☺' }); 200 ``` 201 202 It also works when the charset has been detected in `charsetSentinel` 203 mode. 204 205 ### Parsing Arrays 206 207 **qs** can also parse arrays using a similar `[]` notation: 208 209 ```javascript 210 var withArray = qs.parse('a[]=b&a[]=c'); 211 assert.deepEqual(withArray, { a: ['b', 'c'] }); 212 ``` 213 214 You may specify an index as well: 215 216 ```javascript 217 var withIndexes = qs.parse('a[1]=c&a[0]=b'); 218 assert.deepEqual(withIndexes, { a: ['b', 'c'] }); 219 ``` 220 221 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 222 to create an array. When creating arrays with specific indices, **qs** will compact a sparse array to only the existing values preserving 223 their order: 224 225 ```javascript 226 var noSparse = qs.parse('a[1]=b&a[15]=c'); 227 assert.deepEqual(noSparse, { a: ['b', 'c'] }); 228 ``` 229 230 Note that an empty string is also a value, and will be preserved: 231 232 ```javascript 233 var withEmptyString = qs.parse('a[]=&a[]=b'); 234 assert.deepEqual(withEmptyString, { a: ['', 'b'] }); 235 236 var withIndexedEmptyString = qs.parse('a[0]=b&a[1]=&a[2]=c'); 237 assert.deepEqual(withIndexedEmptyString, { a: ['b', '', 'c'] }); 238 ``` 239 240 **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 241 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. 242 243 ```javascript 244 var withMaxIndex = qs.parse('a[100]=b'); 245 assert.deepEqual(withMaxIndex, { a: { '100': 'b' } }); 246 ``` 247 248 This limit can be overridden by passing an `arrayLimit` option: 249 250 ```javascript 251 var withArrayLimit = qs.parse('a[1]=b', { arrayLimit: 0 }); 252 assert.deepEqual(withArrayLimit, { a: { '1': 'b' } }); 253 ``` 254 255 To disable array parsing entirely, set `parseArrays` to `false`. 256 257 ```javascript 258 var noParsingArrays = qs.parse('a[]=b', { parseArrays: false }); 259 assert.deepEqual(noParsingArrays, { a: { '0': 'b' } }); 260 ``` 261 262 If you mix notations, **qs** will merge the two items into an object: 263 264 ```javascript 265 var mixedNotation = qs.parse('a[0]=b&a[b]=c'); 266 assert.deepEqual(mixedNotation, { a: { '0': 'b', b: 'c' } }); 267 ``` 268 269 You can also create arrays of objects: 270 271 ```javascript 272 var arraysOfObjects = qs.parse('a[][b]=c'); 273 assert.deepEqual(arraysOfObjects, { a: [{ b: 'c' }] }); 274 ``` 275 276 Some people use comma to join array, **qs** can parse it: 277 ```javascript 278 var arraysOfObjects = qs.parse('a=b,c', { comma: true }) 279 assert.deepEqual(arraysOfObjects, { a: ['b', 'c'] }) 280 ``` 281 (_this cannot convert nested objects, such as `a={b:1},{c:d}`_) 282 283 ### Stringifying 284 285 [](#preventEval) 286 ```javascript 287 qs.stringify(object, [options]); 288 ``` 289 290 When stringifying, **qs** by default URI encodes output. Objects are stringified as you would expect: 291 292 ```javascript 293 assert.equal(qs.stringify({ a: 'b' }), 'a=b'); 294 assert.equal(qs.stringify({ a: { b: 'c' } }), 'a%5Bb%5D=c'); 295 ``` 296 297 This encoding can be disabled by setting the `encode` option to `false`: 298 299 ```javascript 300 var unencoded = qs.stringify({ a: { b: 'c' } }, { encode: false }); 301 assert.equal(unencoded, 'a[b]=c'); 302 ``` 303 304 Encoding can be disabled for keys by setting the `encodeValuesOnly` option to `true`: 305 ```javascript 306 var encodedValues = qs.stringify( 307 { a: 'b', c: ['d', 'e=f'], f: [['g'], ['h']] }, 308 { encodeValuesOnly: true } 309 ); 310 assert.equal(encodedValues,'a=b&c[0]=d&c[1]=e%3Df&f[0][0]=g&f[1][0]=h'); 311 ``` 312 313 This encoding can also be replaced by a custom encoding method set as `encoder` option: 314 315 ```javascript 316 var encoded = qs.stringify({ a: { b: 'c' } }, { encoder: function (str) { 317 // Passed in values `a`, `b`, `c` 318 return // Return encoded string 319 }}) 320 ``` 321 322 _(Note: the `encoder` option does not apply if `encode` is `false`)_ 323 324 Analogue to the `encoder` there is a `decoder` option for `parse` to override decoding of properties and values: 325 326 ```javascript 327 var decoded = qs.parse('x=z', { decoder: function (str) { 328 // Passed in values `x`, `z` 329 return // Return decoded string 330 }}) 331 ``` 332 333 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. 334 335 When arrays are stringified, by default they are given explicit indices: 336 337 ```javascript 338 qs.stringify({ a: ['b', 'c', 'd'] }); 339 // 'a[0]=b&a[1]=c&a[2]=d' 340 ``` 341 342 You may override this by setting the `indices` option to `false`: 343 344 ```javascript 345 qs.stringify({ a: ['b', 'c', 'd'] }, { indices: false }); 346 // 'a=b&a=c&a=d' 347 ``` 348 349 You may use the `arrayFormat` option to specify the format of the output array: 350 351 ```javascript 352 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'indices' }) 353 // 'a[0]=b&a[1]=c' 354 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' }) 355 // 'a[]=b&a[]=c' 356 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' }) 357 // 'a=b&a=c' 358 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'comma' }) 359 // 'a=b,c' 360 ``` 361 362 When objects are stringified, by default they use bracket notation: 363 364 ```javascript 365 qs.stringify({ a: { b: { c: 'd', e: 'f' } } }); 366 // 'a[b][c]=d&a[b][e]=f' 367 ``` 368 369 You may override this to use dot notation by setting the `allowDots` option to `true`: 370 371 ```javascript 372 qs.stringify({ a: { b: { c: 'd', e: 'f' } } }, { allowDots: true }); 373 // 'a.b.c=d&a.b.e=f' 374 ``` 375 376 Empty strings and null values will omit the value, but the equals sign (=) remains in place: 377 378 ```javascript 379 assert.equal(qs.stringify({ a: '' }), 'a='); 380 ``` 381 382 Key with no values (such as an empty object or array) will return nothing: 383 384 ```javascript 385 assert.equal(qs.stringify({ a: [] }), ''); 386 assert.equal(qs.stringify({ a: {} }), ''); 387 assert.equal(qs.stringify({ a: [{}] }), ''); 388 assert.equal(qs.stringify({ a: { b: []} }), ''); 389 assert.equal(qs.stringify({ a: { b: {}} }), ''); 390 ``` 391 392 Properties that are set to `undefined` will be omitted entirely: 393 394 ```javascript 395 assert.equal(qs.stringify({ a: null, b: undefined }), 'a='); 396 ``` 397 398 The query string may optionally be prepended with a question mark: 399 400 ```javascript 401 assert.equal(qs.stringify({ a: 'b', c: 'd' }, { addQueryPrefix: true }), '?a=b&c=d'); 402 ``` 403 404 The delimiter may be overridden with stringify as well: 405 406 ```javascript 407 assert.equal(qs.stringify({ a: 'b', c: 'd' }, { delimiter: ';' }), 'a=b;c=d'); 408 ``` 409 410 If you only want to override the serialization of `Date` objects, you can provide a `serializeDate` option: 411 412 ```javascript 413 var date = new Date(7); 414 assert.equal(qs.stringify({ a: date }), 'a=1970-01-01T00:00:00.007Z'.replace(/:/g, '%3A')); 415 assert.equal( 416 qs.stringify({ a: date }, { serializeDate: function (d) { return d.getTime(); } }), 417 'a=7' 418 ); 419 ``` 420 421 You may use the `sort` option to affect the order of parameter keys: 422 423 ```javascript 424 function alphabeticalSort(a, b) { 425 return a.localeCompare(b); 426 } 427 assert.equal(qs.stringify({ a: 'c', z: 'y', b : 'f' }, { sort: alphabeticalSort }), 'a=c&b=f&z=y'); 428 ``` 429 430 Finally, you can use the `filter` option to restrict which keys will be included in the stringified output. 431 If you pass a function, it will be called for each key to obtain the replacement value. Otherwise, if you 432 pass an array, it will be used to select properties and array indices for stringification: 433 434 ```javascript 435 function filterFunc(prefix, value) { 436 if (prefix == 'b') { 437 // Return an `undefined` value to omit a property. 438 return; 439 } 440 if (prefix == 'e[f]') { 441 return value.getTime(); 442 } 443 if (prefix == 'e[g][0]') { 444 return value * 2; 445 } 446 return value; 447 } 448 qs.stringify({ a: 'b', c: 'd', e: { f: new Date(123), g: [2] } }, { filter: filterFunc }); 449 // 'a=b&c=d&e[f]=123&e[g][0]=4' 450 qs.stringify({ a: 'b', c: 'd', e: 'f' }, { filter: ['a', 'e'] }); 451 // 'a=b&e=f' 452 qs.stringify({ a: ['b', 'c', 'd'], e: 'f' }, { filter: ['a', 0, 2] }); 453 // 'a[0]=b&a[2]=d' 454 ``` 455 456 ### Handling of `null` values 457 458 By default, `null` values are treated like empty strings: 459 460 ```javascript 461 var withNull = qs.stringify({ a: null, b: '' }); 462 assert.equal(withNull, 'a=&b='); 463 ``` 464 465 Parsing does not distinguish between parameters with and without equal signs. Both are converted to empty strings. 466 467 ```javascript 468 var equalsInsensitive = qs.parse('a&b='); 469 assert.deepEqual(equalsInsensitive, { a: '', b: '' }); 470 ``` 471 472 To distinguish between `null` values and empty strings use the `strictNullHandling` flag. In the result string the `null` 473 values have no `=` sign: 474 475 ```javascript 476 var strictNull = qs.stringify({ a: null, b: '' }, { strictNullHandling: true }); 477 assert.equal(strictNull, 'a&b='); 478 ``` 479 480 To parse values without `=` back to `null` use the `strictNullHandling` flag: 481 482 ```javascript 483 var parsedStrictNull = qs.parse('a&b=', { strictNullHandling: true }); 484 assert.deepEqual(parsedStrictNull, { a: null, b: '' }); 485 ``` 486 487 To completely skip rendering keys with `null` values, use the `skipNulls` flag: 488 489 ```javascript 490 var nullsSkipped = qs.stringify({ a: 'b', c: null}, { skipNulls: true }); 491 assert.equal(nullsSkipped, 'a=b'); 492 ``` 493 494 If you're communicating with legacy systems, you can switch to `iso-8859-1` 495 using the `charset` option: 496 497 ```javascript 498 var iso = qs.stringify({ æ: 'æ' }, { charset: 'iso-8859-1' }); 499 assert.equal(iso, '%E6=%E6'); 500 ``` 501 502 Characters that don't exist in `iso-8859-1` will be converted to numeric 503 entities, similar to what browsers do: 504 505 ```javascript 506 var numeric = qs.stringify({ a: '☺' }, { charset: 'iso-8859-1' }); 507 assert.equal(numeric, 'a=%26%239786%3B'); 508 ``` 509 510 You can use the `charsetSentinel` option to announce the character by 511 including an `utf8=✓` parameter with the proper encoding if the checkmark, 512 similar to what Ruby on Rails and others do when submitting forms. 513 514 ```javascript 515 var sentinel = qs.stringify({ a: '☺' }, { charsetSentinel: true }); 516 assert.equal(sentinel, 'utf8=%E2%9C%93&a=%E2%98%BA'); 517 518 var isoSentinel = qs.stringify({ a: 'æ' }, { charsetSentinel: true, charset: 'iso-8859-1' }); 519 assert.equal(isoSentinel, 'utf8=%26%2310003%3B&a=%E6'); 520 ``` 521 522 ### Dealing with special character sets 523 524 By default the encoding and decoding of characters is done in `utf-8`, 525 and `iso-8859-1` support is also built in via the `charset` parameter. 526 527 If you wish to encode querystrings to a different character set (i.e. 528 [Shift JIS](https://en.wikipedia.org/wiki/Shift_JIS)) you can use the 529 [`qs-iconv`](https://github.com/martinheidegger/qs-iconv) library: 530 531 ```javascript 532 var encoder = require('qs-iconv/encoder')('shift_jis'); 533 var shiftJISEncoded = qs.stringify({ a: 'こんにちは！' }, { encoder: encoder }); 534 assert.equal(shiftJISEncoded, 'a=%82%B1%82%F1%82%C9%82%BF%82%CD%81I'); 535 ``` 536 537 This also works for decoding of query strings: 538 539 ```javascript 540 var decoder = require('qs-iconv/decoder')('shift_jis'); 541 var obj = qs.parse('a=%82%B1%82%F1%82%C9%82%BF%82%CD%81I', { decoder: decoder }); 542 assert.deepEqual(obj, { a: 'こんにちは！' }); 543 ``` 544 545 ### RFC 3986 and RFC 1738 space encoding 546 547 RFC3986 used as default option and encodes ' ' to *%20* which is backward compatible. 548 In the same time, output can be stringified as per RFC1738 with ' ' equal to '+'. 549 550 ``` 551 assert.equal(qs.stringify({ a: 'b c' }), 'a=b%20c'); 552 assert.equal(qs.stringify({ a: 'b c' }, { format : 'RFC3986' }), 'a=b%20c'); 553 assert.equal(qs.stringify({ a: 'b c' }, { format : 'RFC1738' }), 'a=b+c'); 554 ``` 555 556 [1]: https://npmjs.org/package/qs 557 [2]: http://versionbadg.es/ljharb/qs.svg 558 [3]: https://api.travis-ci.org/ljharb/qs.svg 559 [4]: https://travis-ci.org/ljharb/qs 560 [5]: https://david-dm.org/ljharb/qs.svg 561 [6]: https://david-dm.org/ljharb/qs 562 [7]: https://david-dm.org/ljharb/qs/dev-status.svg 563 [8]: https://david-dm.org/ljharb/qs?type=dev 564 [9]: https://ci.testling.com/ljharb/qs.png 565 [10]: https://ci.testling.com/ljharb/qs 566 [11]: https://nodei.co/npm/qs.png?downloads=true&stars=true 567 [license-image]: http://img.shields.io/npm/l/qs.svg 568 [license-url]: LICENSE 569 [downloads-image]: http://img.shields.io/npm/dm/qs.svg 570 [downloads-url]: http://npm-stat.com/charts.html?package=qs