Compile typescript module to plain web javascript via compiler api

Question

I have a node script where I want to compile a ts file with a exported function to javascript that can be used on the web / embedded into a script tag.

const ts = require("typescript");

// hard coded for demonstration
const typescriptCode = `
export function add(a: number, b: number): number {
    return a + b;
}`;

let result = ts.transpile(typescriptCode, { 
    compilerOptions: { 
        module: ts.ModuleKind.None,
        target: ts.ScriptTarget.ES5
    }
});

However even with ts.ModuleKind.None used in the compile options the program still outputs a script that attempts to bind the function to exports. Exports is not valid on the web. Value of result:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
function add(a, b) {
    return a + b;
}
exports.add = add;

How can I only transpile to this / make result be:

function add(a, b) {
    return a + b;
}

What if you remove the export from the function ? Since you don't want modules you should not use module features such as imports and exports — Titian Cernicova-Dragomir
– Titian Cernicova-Dragomir, Commented Feb 15, 2020 at 21:44
I think you might be looking for something like the answer to this: stackoverflow.com/q/58793176/188246 (there is a transformers property on TranspileOptions). — David Sherret
– David Sherret, Commented Feb 15, 2020 at 22:06
@TitianCernicova-Dragomir Unfortunately that export is required by a separate process. I think my best bet is to remove export keywords from typescriptCode via regex replace before transpile. — Ben
– Ben, Commented Feb 15, 2020 at 22:09

jsejcksn · Accepted Answer · 2020-11-14 23:33:12Z

1

You need to use a different value for module:

const source = `export function add(a: number, b: number): number {
  return a + b;
}`;

transpile(source, { module: 'ESNext', target: 'ESNext' });

Will yield:

export function add(a, b) {
  return a + b;
}

answered Nov 14, 2020 at 23:33

jsejcksn

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