URLSearchParams

The URLSearchParams interface defines utility methods to work with the query string of a URL.

An object implementing URLSearchParams can directly be used in a for...of structure to iterate over key/value pairs in the same order as they appear in the query string, for example the following two lines are equivalent:

for (const [key, value] of mySearchParams) {}
for (const [key, value] of mySearchParams.entries()) {}

Note: This feature is available in Web Workers

Constructor

URLSearchParams(): Returns a URLSearchParams object instance.

Methods

URLSearchParams.append(): Appends a specified key/value pair as a new search parameter.
URLSearchParams.delete(): Deletes the given search parameter, and its associated value, from the list of all search parameters.
URLSearchParams.entries(): Returns an iterator allowing iteration through all key/value pairs contained in this object in the same order as they appear in the query string.
URLSearchParams.forEach(): Allows iteration through all values contained in this object via a callback function.
URLSearchParams.get(): Returns the first value associated with the given search parameter.
URLSearchParams.getAll(): Returns all the values associated with a given search parameter.
URLSearchParams.has(): Returns a boolean value indicating if such a given parameter exists.
URLSearchParams.keys(): Returns an iterator allowing iteration through all keys of the key/value pairs contained in this object.
URLSearchParams.set(): Sets the value associated with a given search parameter to the given value. If there are several values, the others are deleted.
URLSearchParams.sort(): Sorts all key/value pairs, if any, by their keys.
URLSearchParams.toString(): Returns a string containing a query string suitable for use in a URL.
URLSearchParams.values(): Returns an iterator allowing iteration through all values of the key/value pairs contained in this object.

Examples

const paramsString = 'q=URLUtils.searchParams&topic=api';
let searchParams = new URLSearchParams(paramsString);

//Iterate the search parameters.
for (let p of searchParams) {
  console.log(p);
}

searchParams.has('topic') === true;      // true
searchParams.get('topic') === "api";     // true
searchParams.getAll('topic');            // ["api"]
searchParams.get('foo') === null;        // true
searchParams.append('topic', 'webdev');
searchParams.toString();                 // "q=URLUtils.searchParams&topic=api&topic=webdev"
searchParams.set('topic', 'More webdev');
searchParams.toString();                 // "q=URLUtils.searchParams&topic=More+webdev"
searchParams.delete('topic');
searchParams.toString();                 // "q=URLUtils.searchParams"

// Search parameters can also be an object
let paramsObj = {foo: 'bar', baz: 'bar'};
let searchParams = new URLSearchParams(paramsObj);

searchParams.toString();                 // "foo=bar&baz=bar"
searchParams.has('foo');                 // true
searchParams.get('foo');                 // bar

// Having duplicate parameters only returns the first value
let paramStr = 'foo=bar&foo=baz';
let searchParams = new URLSearchParams(paramStr);

searchParams.toString();                 // "foo=bar&foo=baz"
searchParams.has('foo');                 // true
searchParams.get('foo');                 // bar

Gotchas

The URLSearchParams constructor does not parse full URLs. However, it will strip an initial leading ? off of a string, if present.

const paramsString1 = 'http://example.com/search?query=%40';
const searchParams1 = new URLSearchParams(paramsString1);

searchParams1.has('query'); // false
searchParams1.has('http://example.com/search?query'); // true

searchParams1.get('query'); // null
searchParams1.get('http://example.com/search?query'); // "@" (equivalent to decodeURIComponent('%40'))

const paramsString2 = '?query=value';
const searchParams2 = new URLSearchParams(paramsString2);
searchParams2.has('query'); // true

const url = new URL('http://example.com/search?query=%40');
const searchParams3 = new URLSearchParams(url.search);
searchParams3.has('query') // true

It interprets + as a space

const base64 = btoa(String.fromCharCode(19, 224, 23, 64, 31, 128)); // base64 is "E+AXQB+A"
const searchParams = new URLSearchParams('q=foo&bin=' + base64); // q=foo&bin=E+AXQB+A
const getBin = searchParams.get('bin'); // "E AXQB A" + char is replaced by spaces
btoa(atob(getBin)); // "EAXQBA==" no error thrown
btoa(String.fromCharCode(16,5,208,4)) // "EAXQBA==" decodes to wrong binary value
getBin.replace(/ /g, '+'); // "E+AXQB+A" is one solution

// or use set to add the parameter, but this increases the query string length
searchParams.set('bin2', base64) // "q=foo&bin=E+AXQB+A&bin2=E%2BAXQB%2BA" encodes + as %2B
searchParams.get('bin2'); // "E+AXQB+A"

It doesn't distinguish between a parameter with nothing after the = and a parameter that doesn't have a = altogether.

const emptyVal = new URLSearchParams('foo=&bar=baz')
emptyVal.get('foo') // returns ''
const noEquals = new URLSearchParams('foo&bar=baz')
noEquals.get('foo') // also returns ''
noEquals.toString() // 'foo=&bar=baz'

Specifications

Specification
URL Standard # urlsearchparams

Browser compatibility

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