选择器API

//DOM原生 选择器API，IE8、FF3.5、safari3.1、chrome1、opera10支持
var errs = document.querySelectorAll('div.warning,div.notice');

//使用getElementsByTagName()
var errs = [],
    divs = document.getElementsByTagName('div'),
    classname = '';
for (var i = 0, len = divs.length; i < len; i++) {
    classname = divs[i].className;
    if (classname === 'notice' || classname === 'warning') {
        errs.push(divs[i]);
    }
}