# query-string
> Parse and stringify URL [query strings](https://en.wikipedia.org/wiki/Query_string)
---
---
## Install
```
$ npm install query-string
```
This module targets Node.js 6 or later and the latest version of Chrome, Firefox, and Safari. If you want support for older browsers, or, if your project is using create-react-app v1, use version 5: `npm install query-string@5`.
## Usage
```js
const queryString = require('query-string');
console.log(location.search);
//=> '?foo=bar'
const parsed = queryString.parse(location.search);
console.log(parsed);
//=> {foo: 'bar'}
console.log(location.hash);
//=> '#token=bada55cafe'
const parsedHash = queryString.parse(location.hash);
console.log(parsedHash);
//=> {token: 'bada55cafe'}
parsed.foo = 'unicorn';
parsed.ilike = 'pizza';
const stringified = queryString.stringify(parsed);
//=> 'foo=unicorn&ilike=pizza'
location.search = stringified;
// note that `location.search` automatically prepends a question mark
console.log(location.search);
//=> '?foo=unicorn&ilike=pizza'
```
## API
### .parse(string, options?)
Parse a query string into an object. Leading `?` or `#` are ignored, so you can pass `location.search` or `location.hash` directly.
The returned object is created with [`Object.create(null)`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create) and thus does not have a `prototype`.
#### options
Type: `object`
##### decode
Type: `boolean`\
Default: `true`
Decode the keys and values. URL components are decoded with [`decode-uri-component`](https://github.com/SamVerschueren/decode-uri-component).
##### arrayFormat
Type: `string`\
Default: `'none'`
- `'bracket'`: Parse arrays with bracket representation:
```js
const queryString = require('query-string');
queryString.parse('foo[]=1&foo[]=2&foo[]=3', {arrayFormat: 'bracket'});
//=> {foo: ['1', '2', '3']}
```
- `'index'`: Parse arrays with index representation:
```js
const queryString = require('query-string');
queryString.parse('foo[0]=1&foo[1]=2&foo[3]=3', {arrayFormat: 'index'});
//=> {foo: ['1', '2', '3']}
```
- `'comma'`: Parse arrays with elements separated by comma:
```js
const queryString = require('query-string');
queryString.parse('foo=1,2,3', {arrayFormat: 'comma'});
//=> {foo: ['1', '2', '3']}
```
- `'separator'`: Parse arrays with elements separated by a custom character:
```js
const queryString = require('query-string');
queryString.parse('foo=1|2|3', {arrayFormat: 'separator', arrayFormatSeparator: '|'});
//=> {foo: ['1', '2', '3']}
```
- `'none'`: Parse arrays with elements using duplicate keys:
```js
const queryString = require('query-string');
queryString.parse('foo=1&foo=2&foo=3');
//=> {foo: ['1', '2', '3']}
```
##### arrayFormatSeparator
Type: `string`\
Default: `','`
The character used to separate array elements when using `{arrayFormat: 'separator'}`.
##### sort
Type: `Function | boolean`\
Default: `true`
Supports both `Function` as a custom sorting function or `false` to disable sorting.
##### parseNumbers
Type: `boolean`\
Default: `false`
```js
const queryString = require('query-string');
queryString.parse('foo=1', {parseNumbers: true});
//=> {foo: 1}
```
Parse the value as a number type instead of string type if it's a number.
##### parseBooleans
Type: `boolean`\
Default: `false`
```js
const queryString = require('query-string');
queryString.parse('foo=true', {parseBooleans: true});
//=> {foo: true}
```
Parse the value as a boolean type instead of string type if it's a boolean.
### .stringify(object, options?)
Stringify an object into a query string and sorting the keys.
#### options
Type: `object`
##### strict
Type: `boolean`\
Default: `true`
Strictly encode URI components with [strict-uri-encode](https://github.com/kevva/strict-uri-encode). It uses [encodeURIComponent](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent) if set to false. You probably [don't care](https://github.com/sindresorhus/query-string/issues/42) about this option.
##### encode
Type: `boolean`\
Default: `true`
[URL encode](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent) the keys and values.
##### arrayFormat
Type: `string`\
Default: `'none'`
- `'bracket'`: Serialize arrays using bracket representation:
```js
const queryString = require('query-string');
queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'bracket'});
//=> 'foo[]=1&foo[]=2&foo[]=3'
```
- `'index'`: Serialize arrays using index representation:
```js
const queryString = require('query-string');
queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'index'});
//=> 'foo[0]=1&foo[1]=2&foo[2]=3'
```
- `'comma'`: Serialize arrays by separating elements with comma:
```js
const queryString = require('query-string');
queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'comma'});
//=> 'foo=1,2,3'
```
- `'none'`: Serialize arrays by using duplicate keys:
```js
const queryString = require('query-string');
queryString.stringify({foo: [1, 2, 3]});
//=> 'foo=1&foo=2&foo=3'
```
##### arrayFormatSeparator
Type: `string`\
Default: `','`
The character used to separate array elements when using `{arrayFormat: 'separator'}`.
##### sort
Type: `Function | boolean`
Supports both `Function` as a custom sorting function or `false` to disable sorting.
```js
const queryString = require('query-string');
const order = ['c', 'a', 'b'];
queryString.stringify({a: 1, b: 2, c: 3}, {
sort: (a, b) => order.indexOf(a) - order.indexOf(b)
});
//=> 'c=3&a=1&b=2'
```
```js
const queryString = require('query-string');
queryString.stringify({b: 1, c: 2, a: 3}, {sort: false});
//=> 'b=1&c=2&a=3'
```
If omitted, keys are sorted using `Array#sort()`, which means, converting them to strings and comparing strings in Unicode code point order.
##### skipNull
Skip keys with `null` as the value.
Note that keys with `undefined` as the value are always skipped.
Type: `boolean`\
Default: `false`
```js
const queryString = require('query-string');
queryString.stringify({a: 1, b: undefined, c: null, d: 4}, {
skipNull: true
});
//=> 'a=1&d=4'
```
```js
const queryString = require('query-string');
queryString.stringify({a: undefined, b: null}, {
skipNull: true
});
//=> ''
```
##### skipEmptyString
Skip keys with an empty string as the value.
Type: `boolean`\
Default: `false`
```js
const queryString = require('query-string');
queryString.stringify({a: 1, b: '', c: '', d: 4}, {
skipEmptyString: true
});
//=> 'a=1&d=4'
```
```js
const queryString = require('query-string');
queryString.stringify({a: '', b: ''}, {
skipEmptyString: true
});
//=> ''
```
### .extract(string)
Extract a query string from a URL that can be passed into `.parse()`.
Note: This behaviour can be changed with the `skipNull` option.
### .parseUrl(string, options?)
Extract the URL and the query string as an object.
Returns an object with a `url` and `query` property.
If the `parseFragmentIdentifier` option is `true`, the object will also contain a `fragmentIdentifier` property.
```js
const queryString = require('query-string');
queryString.parseUrl('https://foo.bar?foo=bar');
//=> {url: 'https://foo.bar', query: {foo: 'bar'}}
queryString.parseUrl('https://foo.bar?foo=bar#xyz', {parseFragmentIdentifier: true});
//=> {url: 'https://foo.bar', query: {foo: 'bar'}, fragmentIdentifier: 'xyz'}
```
#### options
Type: `object`
The options are the same as for `.parse()`.
Extra options are as below.
##### parseFragmentIdentifier
Parse the fragment identifier from the URL.
Type: `boolean`\
Default: `false`
```js
const queryString = require('query-string');
queryString.parseUrl('https://foo.bar?foo=bar#xyz', {parseFragmentIdentifier: true});
//=> {url: 'https://foo.bar', query: {foo: 'bar'}, fragmentIdentifier: 'xyz'}
```
### .stringifyUrl(object, options?)
Stringify an object into a URL with a query string and sorting the keys. The inverse of [`.parseUrl()`](https://github.com/sindresorhus/query-string#parseurlstring-options)
The `options` are the same as for `.stringify()`.
Returns a string with the URL and a query string.
Query items in the `query` property overrides queries in the `url` property.
The `fragmentIdentifier` property overrides the fragment identifier in the `url` property.
```js
queryString.stringifyUrl({url: 'https://foo.bar', query: {foo: 'bar'}});
//=> 'https://foo.bar?foo=bar'
queryString.stringifyUrl({url: 'https://foo.bar?foo=baz', query: {foo: 'bar'}});
//=> 'https://foo.bar?foo=bar'
queryString.stringifyUrl({
url: 'https://foo.bar',
query: {
top: 'foo'
},
fragmentIdentifier: 'bar'
});
//=> 'https://foo.bar?top=foo#bar'
```
#### object
Type: `object`
##### url
Type: `string`
The URL to stringify.
##### query
Type: `object`
Query items to add to the URL.
### .pick(url, keys, options?)
### .pick(url, filter, options?)
Pick query parameters from a URL.
Returns a string with the new URL.
```js
const queryString = require('query-string');
queryString.pick('https://foo.bar?foo=1&bar=2#hello', ['foo']);
//=> 'https://foo.bar?foo=1#hello'
queryString.pick('https://foo.bar?foo=1&bar=2#hello', (name, value) => value === 2, {parseNumbers: true});
//=> 'https://foo.bar?bar=2#hello'
```
### .exclude(url, keys, options?)
### .exclude(url, filter, options?)
Exclude query parameters from a URL.
Returns a string with the new URL.
```js
const queryString = require('query-string');
queryString.exclude('https://foo.bar?foo=1&bar=2#hello', ['foo']);
//=> 'https://foo.bar?bar=2#hello'
queryString.exclude('https://foo.bar?foo=1&bar=2#hello', (name, value) => value === 2, {parseNumbers: true});
//=> 'https://foo.bar?foo=1#hello'
```
#### url
Type: `string`
The URL containing the query parameters to filter.
#### keys
Type: `string[]`
The names of the query parameters to filter based on the function used.
#### filter
Type: `(key, value) => boolean`
A filter predicate that will be provided the name of each query parameter and its value. The `parseNumbers` and `parseBooleans` options also affect `value`.
#### options
Type: `object`
[Parse options](#options) and [stringify options](#options-1).
## Nesting
This module intentionally doesn't support nesting as it's not spec'd and varies between implementations, which causes a lot of [edge cases](https://github.com/visionmedia/node-querystring/issues).
You're much better off just converting the object to a JSON string:
```js
const queryString = require('query-string');
queryString.stringify({
foo: 'bar',
nested: JSON.stringify({
unicorn: 'cake'
})
});
//=> 'foo=bar&nested=%7B%22unicorn%22%3A%22cake%22%7D'
```
However, there is support for multiple instances of the same key:
```js
const queryString = require('query-string');
queryString.parse('likes=cake&name=bob&likes=icecream');
//=> {likes: ['cake', 'icecream'], name: 'bob'}
queryString.stringify({color: ['taupe', 'chartreuse'], id: '515'});
//=> 'color=taupe&color=chartreuse&id=515'
```
## Falsy values
Sometimes you want to unset a key, or maybe just make it present without assigning a value to it. Here is how falsy values are stringified:
```js
const queryString = require('query-string');
queryString.stringify({foo: false});
//=> 'foo=false'
queryString.stringify({foo: null});
//=> 'foo'
queryString.stringify({foo: undefined});
//=> ''
```
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