javascript - How to use global URLSearchParams in node

Question

I am writing a (client-side) JavaScript library (a node/angular module). In this library, I make use of the URLSearchParams class.

const form = new URLSearchParams();
form.set('username', data.username);
form.set('password', data.pass);

As this is a shared library, it is packed as an npm module. However, when running a mocha unit test, I get the error that URLSearchParams is not defined. The reason seems to be that node does not have URLSearchParams at the global scope, but has to be imported using require('url'):

$ node
> new URLSearchParams()
ReferenceError: URLSearchParams is not defined
    at repl:1:5
    at sigintHandlersWrap (vm.js:22:35)
    at sigintHandlersWrap (vm.js:73:12)
    at ContextifyScript.Script.runInThisContext (vm.js:21:12)
    at REPLServer.defaultEval (repl.js:340:29)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:538:10)
    at emitOne (events.js:101:20)
    at REPLServer.emit (events.js:188:7)

How can I make URLSearchParams available to the client-side code within node, so that I can test the library using mocha?

This is not working:

> global.URLSearchParams = require('url').URLSearchParams
undefined
> new URLSearchParams()
TypeError: URLSearchParams is not a constructor
    at repl:1:1
    at sigintHandlersWrap (vm.js:22:35)
    at sigintHandlersWrap (vm.js:73:12)
    at ContextifyScript.Script.runInThisContext (vm.js:21:12)
    at REPLServer.defaultEval (repl.js:340:29)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:538:10)
    at emitOne (events.js:101:20)
    at REPLServer.emit (events.js:188:7)

Answer 1

Update: Node v10 has built-in availability of URLSearchParams on the global object so it can be used directly as anticipated in the question.

Older versions of Node:

One option is to set it as a global in the start-up script of the test runner:

import { URLSearchParams } from 'url';
global.URLSearchParams = URLSearchParams

With Jest, for example, you would use the setupTestFrameworkScriptFile to point to the above start-up script.

As a side note, if you wanted to achieve a similar outcome when creating a server-side Webpack bundle of universal code you can achieve this with the Webpack ProvidePlugin:

{
  name: 'server',
  target: 'node',
  // ...
  plugins: [
    // ...
    new webpack.ProvidePlugin({
      URLSearchParams: ['url', 'URLSearchParams'],
      fetch: 'node-fetch',
    }),
  ],
}