Lesleh Lesleh - 21 days ago 8
Javascript Question

Using ES5 array methods with ES6 generators

What's the correct way of using the new ES5 array functions with ES6 generators? Do I have to explicitly convert the iterable into an array first, or is there a better way? For example:

function* range(low, high) {
var i = low;
while(i < high)
yield i++;
}

// Sum of numbers in range, doesn't work
console.log(range(0, 10).reduce((x,y) => x + y));

Answer

Generator functions return Iterator objects. The Iterator API does not include higher order Array methods such as map, reduce etc, so you need to build an intermediate Array (or use a library like wu.js).

You can use the spread operator to concisely build an Array from a (finite) iterator:

var sum = [...range(0, 10)].reduce((e, i) => e + i)