Does Deno have a way to shim/polyfill Node.js modules?
That is, let's say I have a typescript file that's part of a Node.js project, and it looks something like this
import { performance } from 'perf_hooks';
function hello() {
console.log(performance.performance.timeOrigin)
console.log("Hello World")
}
export {
hello
}
I want to use this module in a deno program, so I do something like this
import {hello} from './some-module.ts'
function main() {
hello()
}
However, I can't do this because there's no perf_hooks module in Deno.
% deno run main.ts
Check file:///private/tmp/main.ts
error: TS2305 [ERROR]: Module '"deno:///none.d.ts"' has no exported member 'performance'.
import { performance } from 'perf_hooks';
~~~~~~~~~~~
at file:///private/tmp/some-module.ts:1:10
I would like to write my own version of perf_hooks that implements the properties and methods I need, and then tell Deno Hey -- whenever anyone wants perf_hook use my module instead.
Does Deno have anything built in that would let me do this? If not is there some common practive/bundling technique that the Deno community uses to do this sort of thing.
You can use https://deno.land/x/std/node. It provide some Node's built-in modules. For external modules, you can take a look at https://esm.sh (The syntax is https://esm.sh/<npm-pkg>.
And if you want to use it like NodeJS environment, you can do the following:
import { ... } from "module"; // Let's use NodeJS "module" module for this
Then specify an import map
{
"imports": {
"module": "https://deno.land/std/node/module.ts"
}
}
Run with the --import-map flag
$ deno run --import-map=/path/to/import_map.json your_file.ts