breakpoints.js

var mobile = 768;
var tablet = 1280;
var desktop = 1440;

/**
 * Easily check if a breakpoint is active via JavaScript
 *
 * @param {string} breakpoint
 * @returns {boolean}
 */
var isBreakpointActive = function (breakpoint) {
    var isActive = false;
    switch (breakpoint) {
        case 'mobile':
            isActive = (window.innerWidth <= mobile);
            break;
        case 'tablet':
            isActive = (window.innerWidth > mobile && window.innerWidth <= tablet);
            break;
        case 'desktop':
            isActive = (window.innerWidth > tablet);
            break;
    }
    return isActive;
};