3 A querystring parsing and stringifying library with some added security.
5 [![Build Status](https://secure.travis-ci.org/hapijs/qs.svg)](http://travis-ci.org/hapijs/qs)
7 Lead Maintainer: [Nathan LaFreniere](https://github.com/nlf)
9 The **qs** module was originally created and maintained by [TJ Holowaychuk](https://github.com/visionmedia/node-querystring).
14 var Qs = require('qs');
16 var obj = Qs.parse('a=c'); // { a: 'c' }
17 var str = Qs.stringify(obj); // 'a=c'
23 Qs.parse(string, [options]);
26 **qs** allows you to create nested objects within your query strings, by surrounding the name of sub-keys with square brackets `[]`.
27 For example, the string `'foo[bar]=baz'` converts to:
37 When using the `plainObjects` option the parsed value is returned as a plain 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:
40 Qs.parse('a.hasOwnProperty=b', { plainObjects: true });
41 // { a: { hasOwnProperty: 'b' } }
44 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.
47 Qs.parse('a.hasOwnProperty=b', { allowPrototypes: true });
48 // { a: { hasOwnProperty: 'b' } }
51 URI encoded strings work too:
54 Qs.parse('a%5Bb%5D=c');
58 You can also nest your objects, like `'foo[bar][baz]=foobarbaz'`:
70 By default, when nesting objects **qs** will only parse up to 5 children deep. This means if you attempt to parse a string like
71 `'a[b][c][d][e][f][g][h][i]=j'` your resulting object will be:
91 This depth can be overridden by passing a `depth` option to `Qs.parse(string, [options])`:
94 Qs.parse('a[b][c][d][e][f][g][h][i]=j', { depth: 1 });
95 // { a: { b: { '[c][d][e][f][g][h][i]': 'j' } } }
98 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.
100 For similar reasons, by default **qs** will only parse up to 1000 parameters. This can be overridden by passing a `parameterLimit` option:
103 Qs.parse('a=b&c=d', { parameterLimit: 1 });
107 An optional delimiter can also be passed:
110 Qs.parse('a=b;c=d', { delimiter: ';' });
111 // { a: 'b', c: 'd' }
114 Delimiters can be a regular expression too:
117 Qs.parse('a=b;c=d,e=f', { delimiter: /[;,]/ });
118 // { a: 'b', c: 'd', e: 'f' }
121 Option `allowDots` can be used to enable dot notation:
124 Qs.parse('a.b=c', { allowDots: true });
130 **qs** can also parse arrays using a similar `[]` notation:
133 Qs.parse('a[]=b&a[]=c');
137 You may specify an index as well:
140 Qs.parse('a[1]=c&a[0]=b');
144 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
145 to create an array. When creating arrays with specific indices, **qs** will compact a sparse array to only the existing values preserving
149 Qs.parse('a[1]=b&a[15]=c');
153 Note that an empty string is also a value, and will be preserved:
156 Qs.parse('a[]=&a[]=b');
158 Qs.parse('a[0]=b&a[1]=&a[2]=c');
159 // { a: ['b', '', 'c'] }
162 **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
163 instead be converted to an object with the index as the key:
166 Qs.parse('a[100]=b');
167 // { a: { '100': 'b' } }
170 This limit can be overridden by passing an `arrayLimit` option:
173 Qs.parse('a[1]=b', { arrayLimit: 0 });
174 // { a: { '1': 'b' } }
177 To disable array parsing entirely, set `parseArrays` to `false`.
180 Qs.parse('a[]=b', { parseArrays: false });
181 // { a: { '0': 'b' } }
184 If you mix notations, **qs** will merge the two items into an object:
187 Qs.parse('a[0]=b&a[b]=c');
188 // { a: { '0': 'b', b: 'c' } }
191 You can also create arrays of objects:
194 Qs.parse('a[][b]=c');
195 // { a: [{ b: 'c' }] }
201 Qs.stringify(object, [options]);
204 When stringifying, **qs** always URI encodes output. Objects are stringified as you would expect:
207 Qs.stringify({ a: 'b' });
209 Qs.stringify({ a: { b: 'c' } });
213 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.
215 When arrays are stringified, by default they are given explicit indices:
218 Qs.stringify({ a: ['b', 'c', 'd'] });
219 // 'a[0]=b&a[1]=c&a[2]=d'
222 You may override this by setting the `indices` option to `false`:
225 Qs.stringify({ a: ['b', 'c', 'd'] }, { indices: false });
229 You may use the `arrayFormat` option to specify the format of the output array
232 Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'indices' })
234 Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' })
236 Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' })
240 Empty strings and null values will omit the value, but the equals sign (=) remains in place:
243 Qs.stringify({ a: '' });
247 Properties that are set to `undefined` will be omitted entirely:
250 Qs.stringify({ a: null, b: undefined });
254 The delimiter may be overridden with stringify as well:
257 Qs.stringify({ a: 'b', c: 'd' }, { delimiter: ';' });
261 Finally, you can use the `filter` option to restrict which keys will be included in the stringified output.
262 If you pass a function, it will be called for each key to obtain the replacement value. Otherwise, if you
263 pass an array, it will be used to select properties and array indices for stringification:
266 function filterFunc(prefix, value) {
268 // Return an `undefined` value to omit a property.
271 if (prefix == 'e[f]') {
272 return value.getTime();
274 if (prefix == 'e[g][0]') {
279 Qs.stringify({ a: 'b', c: 'd', e: { f: new Date(123), g: [2] } }, { filter: filterFunc })
280 // 'a=b&c=d&e[f]=123&e[g][0]=4'
281 Qs.stringify({ a: 'b', c: 'd', e: 'f' }, { filter: ['a', 'e'] })
283 Qs.stringify({ a: ['b', 'c', 'd'], e: 'f' }, { filter: ['a', 0, 2] })
287 ### Handling of `null` values
289 By default, `null` values are treated like empty strings:
292 Qs.stringify({ a: null, b: '' });
296 Parsing does not distinguish between parameters with and without equal signs. Both are converted to empty strings.
303 To distinguish between `null` values and empty strings use the `strictNullHandling` flag. In the result string the `null`
304 values have no `=` sign:
307 Qs.stringify({ a: null, b: '' }, { strictNullHandling: true });
311 To parse values without `=` back to `null` use the `strictNullHandling` flag:
314 Qs.parse('a&b=', { strictNullHandling: true });
315 // { a: null, b: '' }
319 To completely skip rendering keys with `null` values, use the `skipNulls` flag:
322 qs.stringify({ a: 'b', c: null}, { skipNulls: true })