query-string

Parse and stringify URL query strings

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query-string
Parse and stringify URL query strings



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Install

npm install query-string

!WARNING Remember the hyphen! Do not install the deprecated querystring package!

For browser usage, this package targets the latest version of Chrome, Firefox, and Safari.

Usage

import queryString from '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) 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.
arrayFormat
Type: string\ Default: 'none'
  • 'bracket': Parse arrays with bracket representation:

import queryString from 'query-string';

queryString.parse('foo[]=1&foo[]=2&foo[]=3', {arrayFormat: 'bracket'});
//=> {foo: ['1', '2', '3']}

  • 'index': Parse arrays with index representation:

import queryString from '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:

import queryString from 'query-string';

queryString.parse('foo=1,2,3', {arrayFormat: 'comma'});
//=> {foo: ['1', '2', '3']}

  • 'separator': Parse arrays with elements separated by a custom character:

import queryString from 'query-string';

queryString.parse('foo=1|2|3', {arrayFormat: 'separator', arrayFormatSeparator: '|'});
//=> {foo: ['1', '2', '3']}

  • 'bracket-separator': Parse arrays (that are explicitly marked with brackets) with elements separated by a custom character:

import queryString from 'query-string';

queryString.parse('foo[]', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: []}

queryString.parse('foo[]=', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: ['']}

queryString.parse('foo[]=1', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: ['1']}

queryString.parse('foo[]=1|2|3', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: ['1', '2', '3']}

queryString.parse('foo[]=1||3|||6', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: ['1', '', 3, '', '', '6']}

queryString.parse('foo[]=1|2|3&bar=fluffy&baz[]=4', {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> {foo: ['1', '2', '3'], bar: 'fluffy', baz:['4']}

  • 'colon-list-separator': Parse arrays with parameter names that are explicitly marked with :list:

import queryString from 'query-string';

queryString.parse('foo:list=one&foo:list=two', {arrayFormat: 'colon-list-separator'});
//=> {foo: ['one', 'two']}

  • 'none': Parse arrays with elements using duplicate keys:

import queryString from '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
import queryString from '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
import queryString from '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. It uses encodeURIComponent if set to false. You probably don't care about this option.
encode
Type: boolean\ Default: true
URL encode the keys and values.
arrayFormat
Type: string\ Default: 'none'
  • 'bracket': Serialize arrays using bracket representation:

import queryString from 'query-string';

queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'bracket'});
//=> 'foo[]=1&foo[]=2&foo[]=3'

  • 'index': Serialize arrays using index representation:

import queryString from '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:

import queryString from 'query-string';

queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'comma'});
//=> 'foo=1,2,3'

queryString.stringify({foo: [1, null, '']}, {arrayFormat: 'comma'});
//=> 'foo=1,,'
// Note that typing information for null values is lost
// and `.parse('foo=1,,')` would return `{foo: [1, '', '']}`.

  • 'separator': Serialize arrays by separating elements with a custom character:

import queryString from 'query-string';

queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'separator', arrayFormatSeparator: '|'});
//=> 'foo=1|2|3'

  • 'bracket-separator': Serialize arrays by explicitly post-fixing array names with brackets and separating elements with a custom character:

import queryString from 'query-string';

queryString.stringify({foo: []}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]'

queryString.stringify({foo: ['']}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]='

queryString.stringify({foo: [1]}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]=1'

queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]=1|2|3'

queryString.stringify({foo: [1, '', 3, null, null, 6]}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]=1||3|||6'

queryString.stringify({foo: [1, '', 3, null, null, 6]}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|', skipNull: true});
//=> 'foo[]=1||3|6'

queryString.stringify({foo: [1, 2, 3], bar: 'fluffy', baz: [4]}, {arrayFormat: 'bracket-separator', arrayFormatSeparator: '|'});
//=> 'foo[]=1|2|3&bar=fluffy&baz[]=4'

  • 'colon-list-separator': Serialize arrays with parameter names that are explicitly marked with :list:

import queryString from 'query-string';

queryString.stringify({foo: ['one', 'two']}, {arrayFormat: 'colon-list-separator'});
//=> 'foo:list=one&foo:list=two'

  • 'none': Serialize arrays by using duplicate keys:

import queryString from '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.
import queryString from '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'

import queryString from '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
import queryString from 'query-string';

queryString.stringify({a: 1, b: undefined, c: null, d: 4}, {
	skipNull: true
});
//=> 'a=1&d=4'

import queryString from 'query-string';

queryString.stringify({a: undefined, b: null}, {
	skipNull: true
});
//=> ''
skipEmptyString
Skip keys with an empty string as the value.
Type: boolean\ Default: false
import queryString from 'query-string';

queryString.stringify({a: 1, b: '', c: '', d: 4}, {
	skipEmptyString: true
});
//=> 'a=1&d=4'

import queryString from '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.
import queryString from '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
import queryString from '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()
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.
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.
import queryString from '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.
import queryString from '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 and stringify options.

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.
You're much better off just converting the object to a JSON string:
import queryString from '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:
import queryString from '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:
import queryString from 'query-string';

queryString.stringify({foo: false});
//=> 'foo=false'

queryString.stringify({foo: null});
//=> 'foo'

queryString.stringify({foo: undefined});
//=> ''

FAQ

Why is it parsing + as a space?

See this answer.