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                // TypeScript - foreach with index : yield based conversion example

class Entry<T> {
    public constructor(public index: number, public item: T) {
        // nothing here...

function* mapArray<T>(array: Array<T>): IterableIterator<Entry<T>> {
    for(let i = 0; i < array.length; ++i)
        yield new Entry(i, array[i]);

// Example:

// This is ES6 version 

let array : Array<string> = ['a', 'b', 'c'];

for(let {index, item} of mapArray(array))
    console.log(`${index} : ${item}`);

// This is alternative version for codepen

let array : Array<string> = ['a', 'b', 'c'];
let entries = mapArray(array);

for(let entry =; !entry.done; entry = {
  let value = entry.value;
  console.log(`${value.index} : ${value.item}`);