URLSearchParams.append()

The append() method of the URLSearchParams interface appends a specified key/value pair as a new search parameter.

As shown in the example below, if the same key is appended multiple times it will appear in the parameter string multiple times for each value.

URLSearchParams.append(name, value)

name

The name of the parameter to append.

value 

The value of the parameter to append.

Void.

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

//Add a second foo parameter.
params.append('foo', 4);
//Query string is now: 'foo=1&bar=2&foo=4'

• Other URL-related interfaces: URL, HTMLHyperlinkElementUtils.
• Google Developers: Easy URL manipulation with URLSearchParams