javascript document.getElementsByClassName compatibility with IE

Question

What is the best method to retrieve an array of elements that have a certain class?

I would use document.getElementsByClassName but IE does not support it.

Answer 1

You can't really replicate getElementsByClassName, because it returns a nodeList, and so its value is live, and updates with the document.

You can return a static Array of elements who share the same classnames- but it won't 'know'when the document changes.

(It won't take too many of these kind of things to make a library look svelte...)

function getArrayByClassNames(classes, pa){
    if(!pa) pa= document;
    var C= [], G;
    if(pa.getElementsByClassName){
        G= pa.getElementsByClassName(classes);
        for(var i= 0, L= G.length; i<L; i++){
            C[i]= G[i];
        }
    }
    else{
        classes= classes.split(/\s+/);
        var who, cL= classes.length,
        cn, G= pa.getElementsByTagName('*'), L= G.length;
        for(var i= 0; i<cL; i++){
            classes[i]= RegExp('\\b'+classes[i]+'\\b');
        }
        classnameLoop:
        while(L){
            who= G[--L];
            cn= who.className;
            if(cn){
                for(var i= 0; i<cL; i++){
                    if(classes[i].test(cn)== false) {
                        continue classnameLoop;
                    }
                }
                C.push(who);
            }
        }
    }
    return C;
}

//Example

var A= getArrayByClassNames('sideBar local')