web-module-loader v0.1.6

Web module loader

This package loads commonjs modules at runtime. It's intended to immitate node's module loading in the browser. It will also work within node.

Installation

npm install --save web-module-loader

Usage

There are two APIs:

• loader - A higher-level API that allows providing top-level modules by name (e.g. moment), and registers exports as scripts are evaluated.
• evaluate - A lower-level API that allows passing a require function and then evaluating a script that can look up modules by calling the provided require.

Loader

Requiring top-level modules

If moment is installed, for example:

import loader from "web-module-loader";
import moment from "moment";

const context = loader({ moment });

const script = `
const moment = require('moment');

module.exports = moment(1111111111111).format('MM/DD/YY');
`;

const result = context()(script);

console.log(result); // => 03/17/05

Multiple scripts

Scripts can require one another by relative path:

import loader from "web-module-loader";

const context = loader();

const scriptA = "module.exports = 1;";
const scriptB = "module.exports = 2 + require('./a');";
const scriptC = "module.exports = 3 + require('../b');";

context("a.js")(scriptA);
context("b.js")(scriptB);
const result = context("foo/c.js")(scriptC);

console.log(result); // => 6;

Evaluate

Exporting values

import { evaluate } from "web-module-loader";

const result = evaluate()("module.exports = 3;");

console.log(result); // => 3

Requiring modules

If moment is installed, for example:

import { evaluate } from "web-module-loader";
import moment from "moment";

const require = name => {
  switch (name) {
    case "moment":
      return moment;
    default:
      throw new Error(`Module ${name} not found!`);
  }
};

const script = `
module.exports = moment(1111111111111).format('MM/DD/YY');
`;

const result = evaluate(require)(script);

console.log(result); // => 03/17/05

Storing exported modules

If you want to evaluate multiple files that can require one another, consider creating an object to store exports by name:

import { evaluate } from "web-module-loader";

const moduleMap = {};

const require = name => {
  if (name in moduleMap) {
    return moduleMap[name];
  }

  throw new Error(`Module ${name} not found!`);
};

const scriptA = "module.exports = 3;";
const scriptB = "module.exports = 4 + require('a')";

const bundler = evaluate(require);
moduleMap.a = bundler(scriptA);
moduleMap.b = bundler(scriptB);

console.log(moduleMap.b); // => 7