getElementsByAttribute.js

var getElementsByAttribute = function (tagname, attr, value) {
    if (arguments.length < 3) {
        value = attr;
        attr = tagname;
        tagname = '*';
    }
    var match = [];
    var eles = document.getElementsByTagName(tagname);
    var i = eles.length;
    while (i) {
        i -= 1;
        if (eles[i].hasAttribute(attr)) {
            if (!value || eles[i].getAttribute(attr) === value) {
                match.push(eles[i]);
            }
        }
    }
    return match;
};