Takes a screen dimension and return its ratio as width:height

toRatio.js

/**
 * toRatio.js
 * Copyright (c) 2015 marlun78
 * MIT License, https://gist.github.com/marlun78/bd0800cf5e8053ba9f83
 * 
 * Takes a screen dimension and return its ratio as width:height.
 * 
 * @example 
 * toRatio(1280, 720); //=> 16:9
 * toRatio(800, 600); //=> 4:3
 * 
 * @param {number} width
 * @param {number} height
 * @returns {string}
 */
function toRatio(width, height) {
    if (width % 10 === 0 && height % 10 === 0) {
        return toRatio(width / 10, height / 10);
    } else if (width % 2 === 0 && height % 2 === 0) {
        return toRatio(width / 2, height / 2);
    } else {
        return width + ':' + height;
    }
}