iterator.02.js

iterator.02.js

function makeRangeIterator(start = 0, end = Infinity, step = 1) {
    var nextIndex = start;
    var n = 0;
    
    var rangeIterator = {
       next: function() {
           var result;
           if (nextIndex < end) {
               result = { value: nextIndex, done: false }
           } else if (nextIndex == end) {
               result = { value: n, done: true }
           } else {
               result = { done: true };
           nextIndex += step;
           n++;
           return result;
       }
    };
    return rangeIterator;
}

// run iterator
const it = makeRangeIterator(1, 4);

let result = it.next();
while (!result.done) {
    console.log(result.value); // 1 2 3
    result = it.next();
}