Get common factors of an array of numbers

arrayFactors.js

function getCommonFactorsOf(arrayOfNumbers) {
	var numbers = arrayOfNumbers;
	var length = numbers.length;

	var minor = 0;
	for (let i=0; i < length; i++) {
		let number = numbers[i];
		if (i===0 || number < minor) {
			minor = number;
		}
	}

	var arrFactors = [];
	for (let i=0; i < length; i++) {

		let factor = numbers[i];
		let isFactor = factor <= minor ? true : false;
		let iterator = 0;

		while (isFactor === true && iterator < length) {
			let number = numbers[iterator];
			let result = number % factor === 0;
			if (!result) {
				isFactor = false;
			}
			iterator++;
		}
		if (isFactor === true) {
			arrFactors.push(number);
		}
	}

	return arrFactors.length ? arrFactors : null;
}