range.js

range.js

const range = function* (stop = 0, step = 1) {
    const shouldStop = (n)=>stop >= 0 ? (n < stop) : (n > stop);
    const interval = (n)=>stop >= 0 ? n + step : n - step;
    let itr = function*() {
        let i = 0;
        while (shouldStop(i)) {
            yield i;
            i = interval(i);
        }
    };
    
    itr[Symbol.iterator] = itr;
    yield* itr;
};

for (let i of range(5))
    console.log(i);

for (let i of range(-5))
    console.log(i);

[...range(5)]

How about:

function* range(start, stop, step = 1) {
  let counter = start;
  let direction = stop > 0;
  while (counter < stop === direction && counter !== stop) {
    yield counter;
    counter += step;
  }
}