@lopatnov/make-iterable

A TypeScript library that converts objects, functions, and their prototypes into Array-like iterable entities. Apply it to a class prototype and every instance becomes iterable automatically.

Installation
Usage
API
Examples
Demo
Contributing
Built With
License

Installation

npm install @lopatnov/make-iterable

Browser (CDN):

<script src="//lopatnov.github.io/make-iterable/dist/make-iterable.umd.min.js"></script>

Usage

ES Modules

import makeIterable from "@lopatnov/make-iterable";

CommonJS

const makeIterable = require("@lopatnov/make-iterable");

Browser / UMD

<script src="make-iterable.umd.min.js"></script>
<script>
  // available as window.makeIterable
  var x = makeIterable({});
</script>

API

function makeIterable<T>(value: T): T & Array<any>;

Converts value to an Array-like iterable object in place and returns it. The original object reference is preserved — value === makeIterable(value).

The function attaches all Array.prototype methods (push, pop, splice, slice, indexOf, map, filter, forEach, etc.) and implements Symbol.iterator, enabling for...of loops and the spread operator.

Throws Error when value is undefined, null, a boolean, a number, or a string.

Examples

Make an Object Iterable and Array-Like

const x = { hello: "world" };
const iterableX = makeIterable(x);

iterableX.push(10); // [10]
iterableX.push(20); // [10, 20]
iterableX.push(30); // [10, 20, 30]
iterableX.push(40); // [10, 20, 30, 40]
iterableX.pop(); // [10, 20, 30]

for (const index in x) {
  console.log(`Index [${index}] = ${x[index]}`);
  // "Index [0] = 10"
  // "Index [1] = 20"
  // "Index [2] = 30"
  // "Index [hello] = world"
}

for (const value of x) {
  console.log(value); // 10, 20, 30
}

console.log(x === iterableX); // true
console.log(iterableX.indexOf(30)); // 2
console.log([...iterableX]); // [10, 20, 30]
console.log(iterableX.hello); // "world"

Make a Class Iterable via Prototype

class Simple {
  constructor(public message: string) {}
}

makeIterable(Simple.prototype);

const z = new Simple("Length is not enumerable now") as Simple & any[];
z.push([1, 2], [3, 4], [5, 6]);

for (const index in z) {
  console.log(`z[${index}]=${z[index]}`);
  // "z[0]=1,2"
  // "z[1]=3,4"
  // "z[2]=5,6"
  // "z[message]=Length is not enumerable now"
}

Make a Function Iterable

const fn = function () {};
const iterableFn = makeIterable(fn);

iterableFn.push(1, 2, 3, 4, 5);
console.log(iterableFn.indexOf(3)); // 2
console.log([...iterableFn]); // [1, 2, 3, 4, 5]

Demo

Contributing

Contributions are welcome! Please read CONTRIBUTING.md before opening a pull request.

Bug reports → open an issue
Questions → Discussions
Found it useful? A star on GitHub helps others discover the project

Built With

TypeScript — strict typing throughout
Rollup — bundled to ESM, CJS, and UMD formats
Node.js Test Runner — built-in test runner, zero dependencies
OXLint — fast JavaScript/TypeScript linter
oxfmt — code formatter