Skip to main content

Using jsdom with Deno

jsdom is a pure JavaScript implementation of many web standards, notably the WHATWG DOM and HTML Standards. It's main goal is to be comprehensive and standards compliant and does not specifically consider performance.

If you are interested in server side rendering, then both deno-dom and LinkeDOM are better choices. If you are trying to run code in a "virtual" browser that needs to be standards based, then it is possible that jsdom is suitable for you.

While jsdom works under the Deno CLI, it does not type check. This means you have to use the --no-check=remote option on the command line to avoid diagnostics stopping the execution of your programme.

Having sound typing in an editor requires some changes to the workflow as well, as the way jsdom types are provided are declared as a global type definition with a globally named module, as well as leveraging the built in types from the built-in DOM libraries.

This means if you want strong typing and intelligent auto-completion in your editor while using the Deno language server, you have to perform some extra steps.

Defining an import_map.json​

You need to map the bare specifier "jsdom" to the imported version of jsdom. This allows Deno to correctly apply the types to the import in the way they were specified.

{
  "jsdom": "https://esm.sh/jsdom"
}

Setting up a configuration file​

You will want to set up a deno.jsonc configuration file in the root of your workspace with both TypeScript library information as well as specifying the import map defined above:

{
  "compilerOptions": {
    "lib": [
      "deno.ns",
      "dom",
      "dom.iterable",
      "dom.asynciterable"
    ]
  },
  "importMap": "./import_map.json"
}

Note: we are using an unpinned version of jsdom above. You should consider pinning the version to the version you know you want to use.

Basic example​

This example will take a test string and parse it as HTML and generate a DOM structure based on it. It will then query that DOM structure, picking out the first heading it encounters and print out the text content of that heading:

import { JSDOM } from "jsdom";
import { assert } from "https://deno.land/std@0.221.0/assert/mod.ts";

const { window: { document } } = new JSDOM(
  `<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Hello from Deno</title>
  </head>
  <body>
    <h1>Hello from Deno</h1>
    <form>
      <input name="user">
      <button>
        Submit
      </button>
    </form>
  </body>
</html>`,
  {
    url: "https://example.com/",
    referrer: "https://example.org/",
    contentType: "text/html",
    storageQuota: 10000000,
  },
);

const h1 = document.querySelector("h1");
assert(h1);

console.log(h1.textContent);