JS range function like in python

range.js

function range(start, stop, step=1) {
	let length = 0;
	if(arguments.length == 1) {
		[start, stop, step] = [0, start, 1];
	}
	
	[start, stop, step] = [start, stop, step].map(Math.floor);
	
	if(step === 0) 
		throw new TypeError("step cannot be zero");
	
	if(step > 0 && start < stop) {
		length = Math.floor(1 + (stop - 1 - start) / step);
	} else if(step < 0 && start > stop) {
		length = Math.floor(1 + (start - 1 - stop) / -step);
	}
	
	let ret = {
		contains(val) {
			return start < val && val < stop;
		},
		[Symbol.iterator]() {
			let idx = 0;
			return {
				next() {
					let value = start + idx++ * step;
					let done = idx > length;
					return {value, done};
				}
			};
		}
	};
	
	Object.defineProperty(ret, "length", {
		"writable": false,
		"value": length
	});
	
	return ret;
}