DOM selector

gistfile1.js

//Returns an object reference to the identified element.
function id(i){
    return document.getElementById(i);
}
//Returns a list of elements with the given tag name.
function tagName(t){
    return document.getElementsByTagName(t);
}
//Returns a list of elements with the given name.
function name(n){
    return document.getElementsByName(n);
}
//Returns a set of elements which have all the given class names. 
function className(classname, parentNode) {
    var parentNode = parentNode || document;
    if(document.getElementsByClassName) return parentNode.getElementsByClassName(classname);
    var classnameArr = classname.replace(/^\s+|\s+$/g,"").split(/\s+/);
    if(document.querySelectorAll) {
        var classname = "." + classnameArr.join(".");
        return parentNode.querySelectorAll(classname);
    }
    var allTags = parentNode.getElementsByTagName("*");
    var nodes = [];
    if(allTags.length) {
        tagLoop:
        for(var i = 0; i < allTags.length; i++) {
            var tmpTag = allTags[i];
            var tmpClass = tmpTag.className;
            if(!tmpClass) continue tagLoop;
            if (tmpClass === classname) {
                nodes.push(tmpTag);
                continue tagLoop;
            }
            matchLoop:
            for(var j = 0; j < classnameArr.length; j++) {
                var patt = new RegExp("\\b" + classnameArr[j] + "\\b");
                if(!patt.test(tmpClass)) {
                    continue tagLoop;
                }
            }
            nodes.push(tmpTag);
        }
    }
    return nodes;
}