query-string

Parse and stringify URL query strings

^{My open source work is supported by the community}

^{Special thanks to:}

All your environment variables, in one place

Stop struggling with scattered API keys, hacking together home-brewed tools,
and avoiding access controls. Keep your team and servers in sync with Doppler.

Strapi is the leading open-source headless CMS.

^{It’s 100% JavaScript, fully customizable, and developer-first.}

^{Founded in 2018, OSS Capital is the first and only venture capital platform focused
exclusively on supporting early-stage COSS (commercial open source) startup founders.}

Install

$ npm install query-string

Not

npm install querystring

This module targets Node.js 6 or later and the latest version of Chrome, Firefox, and Safari.

Usage

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

?

#

location.search

location.hash

The returned object is created with

Object.create(null)

prototype

options

Type:

object

decode

Type:

boolean

true

Decode the keys and values. URL components are decoded with

decode-uri-component

arrayFormat

Type:

string

'none'

• 'bracket'

  : Parse arrays with bracket representation:

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:

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:

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:

const queryString = require('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:

const queryString = require('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']}

• 'none'

  : Parse arrays with elements using duplicate keys:

const queryString = require('query-string');

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

arrayFormatSeparator

Type:

string

','

The character used to separate array elements when using

{arrayFormat: 'separator'}

sort

Type:

Function | boolean

true

Supports both

Function

false

parseNumbers

Type:

boolean

false

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

false

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

true

Strictly encode URI components with strict-uri-encode. It uses encodeURIComponent if set to false. You probably don't care about this option.

encode

Type:

boolean

true

URL encode the keys and values.

arrayFormat

Type:

string

'none'

• 'bracket'

  : Serialize arrays using bracket representation:

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:

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:

const queryString = require('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:

const queryString = require('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:

const queryString = require('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'

• 'none'

  : Serialize arrays by using duplicate keys:

const queryString = require('query-string');

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

arrayFormatSeparator

Type:

string

','

The character used to separate array elements when using

{arrayFormat: 'separator'}

sort

Type:

Function | boolean

Supports both

Function

false

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'

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()

skipNull

Skip keys with

null

Note that keys with

undefined

Type:

boolean

false

const queryString = require('query-string');

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

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

false

const queryString = require('query-string');

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

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

.parseUrl(string, options?)

Extract the URL and the query string as an object.

Returns an object with a

url

query

If the

parseFragmentIdentifier

true

fragmentIdentifier

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

false

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()

The

options

.stringify()

Returns a string with the URL and a query string.

Query items in the

query

url

The

fragmentIdentifier

url

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.

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.

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

parseBooleans

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:

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:

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:

const queryString = require('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.

query-string for enterprise

Available as part of the Tidelift Subscription.

The maintainers of query-string and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.