selector.js

//wasting
var rx = {
    id: /^#([\w\-]+)$/,
    className: /^\.([\w\-]+)$/,
    tagName: /^[\w\-]+$/,
    name: /^\[name=["']?([\w\-]+)["']?\]$/
};

var nativeSlice = [].slice;

//select element with filtering id, className, tagName, name selector.
function select(selector, context) {
    var result, m;
    if(!context || !context.querySelector) {
        context = document;
    }
    if(m = rx.id.exec(selector)) {
        var element = document.getElementById(m[1]);
        if(element) {
            result = [element];
        } else {
            result = [];
        }
    } else if(m = rx.className.exec(selector)) {
        result = context.getElementsByClassName(m[1]);
    } else if(m = rx.tagName.exec(selector)) {
        result = context.getElementsByTagName(m[1]);
    } else if(m = rx.name.exec(selector)) {
        result = context.getElementsByName(m[1]);
    } else {
        result = context.querySelectorAll(selector);
    }
    return nativeSlice.call(result);
};