How to replace Deno.env calls when bundling - deno

Question

I'm attempting to build a script to be run in the browser and I wish to replace Deno.env.get(...) calls with the actual value I'm passing.
Does Deno have a built in way to handle this?
My expectation was something like:
// mod.ts
console.log(Deno.env.get('MY_VAR'));
# in terminal
MY_VAR=hello deno bundle --allow-env mod.ts bundle.js
// bundle.js
console.log("hello") // this doesn't happen.. still Deno.env.get('MY_VAR')

Answer 1

Deno has no built-in way to replace Deno.env.get(...) when bunding.
So I wrote my own build script that only handles strings.
// build.ts
interface BuildParams {
input: string;
output: string;
env: Record<string, string>;
}
const build = async ({ input, output, env }: BuildParams) => {
const process = Deno.run({
cmd: [
"deno",
"bundle",
input,
output,
],
});
await process.status();
const bundle = await Deno.readTextFile(output);
const parsedBundle = Object.entries(env).reduce(
(acc, [key, value]) => {
const searchString = `Deno\\.env\\.get\\("${key}"\\)`;
const regExp = new RegExp(searchString, "g");
acc = acc.replace(regExp, `"${value}"`);
return acc;
},
bundle,
);
await Deno.writeTextFile(output, parsedBundle);
};
export default build;
And an example usage:
await build({
input: Deno.cwd() + "/lib/mod.ts",
output: Deno.cwd() + "/public/javascript/build/upc-bundle.js",
env: {
SERVER_URL: Deno.env.get("SERVER_URL") ?? "ws://127.0.0.1:3012",
}
});