Node.js URLSearchParams.set()

Last Updated : 10 Aug, 2026

The URLSearchParams.set() method in Node.js is used to set a new value for a specific key in a URL’s query string. If the key already exists, its value is replaced.

  • It sets or updates the value of a parameter.
  • It replaces any existing values for the same key.
  • It keeps the query string simple and updated.

Syntax:

urlSearchParams.set(name, value)

Where,

  • urlSearchParams: An instance of the URLSearchParams class that stores query parameters.
  • set(name, value): A method that assigns a value to the given parameter name.

Return Value: The method does not return any value and returns undefined.

Example 1:

javascript 
let url = new URL('https://example.com/?fo=4&bar=6');
let params = new URLSearchParams(url.search.slice(1));

//Add another parameter.
params.set('par', 5);
console.log(params.toString());

Output:

fo=4&bar=6&par=5

Example 2:

javascript 
let url = new URL('https://example.com/?a=1&b=2');
let params = new URLSearchParams(url.search.slice(1));

//Add another parameter.
params.set('c', 3);
params.set('d', 4);
console.log(params.toString());

Output: 

a=1&b=2&c=3&d=4

Use Cases of URLSearchParams.set():

  • It is used to update the value of an existing query parameter.
  • It is used to remove duplicate values by replacing them with a single value.
  • It is used to modify query strings before making requests.
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