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.

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';
const searchParams = new URLSearchParams(paramsString);

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

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

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

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

Duplicate search parameters

const paramStr = 'foo=bar&foo=baz';
const searchParams = new URLSearchParams(paramStr);

console.log(searchParams.toString());                 // "foo=bar&foo=baz"
console.log(searchParams.has('foo'));                 // true
console.log(searchParams.get('foo'));                 // bar, only returns the first value
console.log(searchParams.getAll('foo'));              // ["bar", "baz"]

No URL parsing

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);

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

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

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

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

Preserving plus signs

The URLSearchParams constructor interprets plus signs (+) as spaces, which might cause problems.

const rawData = '\x13à\x17@\x1F\x80';
const base64Data = btoa(rawData); // 'E+AXQB+A'

const searchParams = new URLSearchParams(`bin=${base64Data}`); // 'bin=E+AXQB+A'
const binQuery = searchParams.get('bin'); // 'E AXQB A', '+' is replaced by spaces

console.log(atob(binQuery) === rawData); // false

You can avoid this by encoding the data with the encodeURIComponent().

const rawData = '\x13à\x17@\x1F\x80';
const base64Data = btoa(rawData); // 'E+AXQB+A'
const encodedBase64Data = encodeURIComponent(base64Data); // 'E%2BAXQB%2BA'

const searchParams = new URLSearchParams(`bin=${encodedBase64Data}`); // 'bin=E%2BAXQB%2BA'
const binQuery = searchParams.get('bin'); // 'E+AXQB+A'

console.log(atob(binQuery) === rawData); // true

Empty value vs. no value

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

Specifications

Specification
URL Standard # urlsearchparams

Browser compatibility

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