JavaScript Media Query or jsMQ is a function that can tell you what the current state of the browser is (Small, Medium or Large) and notify you if there is a change.

jsMQ.js

jsMQcallback = $.Callbacks(), jsMQcurrent = "";
var jsMQ = {
    getVW : function(){
        vw=jQuery(window).width();
        if(vw  <= 480) return "s";
        if((vw >= 480) && (vw <= 748)) return "sl";
        if((vw >= 749) && (vw <= 965)) return "m";
        if(vw  >= 966) return "l"; 
    },
    pubVW : function(){
        vw = jsMQ.getVW(); 
        if(jsMQcurrent != vw){
            jsMQcurrent = vw;
            jsMQcallback.fire(vw);
        }
    },
    isSmall  : function(){ return ( jsMQ.getVW().charAt(0)=="s" ) ? true : false; },
    isMedium : function(){ return ( jsMQ.getVW()=="m" ) ? true : false; },
    isLarge  : function(){ return ( jsMQ.getVW()=="l" ) ? true : false; }
};
setInterval(jsMQ.pubVW, 1800);

What is unique about this solution is that you can leverage JavaScript to fire events when the size of the browser changes even after the page has loaded.

Requires JQuery.
See also: https://api.jquery.com/jQuery.Callbacks/