# query-string [](https://travis-ci.org/sindresorhus/query-string)
> Parse and stringify URL [query strings](http://en.wikipedia.org/wiki/Query_string)
---
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---
## Install
```
$ npm install --save query-string
```
## 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`.
#### arrayFormat
Type: `string`
Default: `'none'`
Supports both `index` for an indexed array representation or `bracket` for a *bracketed* array representation.
- `bracket`: stands for parsing correctly arrays with bracket representation on the query string, such as:
```js
queryString.parse('foo[]=1&foo[]=2&foo[]=3', {arrayFormat: 'bracket'});
//=> foo: [1,2,3]
```
- `index`: stands for parsing taking the index into account, such as:
```js
queryString.parse('foo[0]=1&foo[1]=2&foo[3]=3', {arrayFormat: 'index'});
//=> foo: [1,2,3]
```
- `none`: is the **default** option and removes any bracket representation, such as:
```js
queryString.parse('foo=1&foo=2&foo=3');
//=> foo: [1,2,3]
```
### .stringify(*object*, *[options]*)
Stringify an object into a query string, sorting the keys.
#### 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'`
Supports both `index` for an indexed array representation or `bracket` for a *bracketed* array representation.
- `bracket`: stands for parsing correctly arrays with bracket representation on the query string, such as:
```js
queryString.stringify({foo: [1,2,3]}, {arrayFormat: 'bracket'});
// => foo[]=1&foo[]=2&foo[]=3
```
- `index`: stands for parsing taking the index into account, such as:
```js
queryString.stringify({foo: [1,2,3]}, {arrayFormat: 'index'});
// => foo[0]=1&foo[1]=2&foo[3]=3
```
- `none`: is the __default__ option and removes any bracket representation, such as:
```js
queryString.stringify({foo: [1,2,3]});
// => foo=1&foo=2&foo=3
```
### .extract(*string*)
Extract a query string from a URL that can be passed into `.parse()`.
## 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
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
queryString.parse('likes=cake&name=bob&likes=icecream');
//=> {likes: ['cake', 'icecream'], name: 'bob'}
queryString.stringify({color: ['taupe', 'chartreuse'], id: '515'});
//=> 'color=chartreuse&color=taupe&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
queryString.stringify({foo: false});
//=> 'foo=false'
queryString.stringify({foo: null});
//=> 'foo'
queryString.stringify({foo: undefined});
//=> ''
```
## License
MIT © [Sindre Sorhus](https://sindresorhus.com)