if (!document.querySelectorAll) {
document.querySelectorAll = function (selectors) {
var style = document.createElement("style"), elements = [], element;
document.documentElement.firstChild.appendChild(style);
document._qsa = [];
style.styleSheet.cssText = selectors + '{x-qsa:expression(document._qsa && document._qsa.push(this))}';
window.scrollBy(0, 0);
style.parentNode.removeChild(style);
while (document._qsa.length) {
element = document._qsa.shift();
element.style.removeAttribute('x-qsa');
elements.push(element);
}
document._qsa = null;
return elements;
};
}
if (!document.querySelector) {
document.querySelector = function (selectors) {
var elements = document.querySelectorAll(selectors);
return (elements.length) ? elements[0] : null;
};
}
// 用于在IE6和IE7浏览器中,支持Element.querySelectorAll方法
var qsaWorker = (function () {
var idAllocator = 10000;
function qsaWorkerShim(element, selector) {
var needsID = element.id === "";
if (needsID) {
++idAllocator;
element.id = "__qsa" + idAllocator;
}
try {
return document.querySelectorAll("#" + element.id + " " + selector);
}
finally {
if (needsID) {
element.id = "";
}
}
}
function qsaWorkerWrap(element, selector) {
return element.querySelectorAll(selector);
}
// Return the one this browser wants to use
return document.createElement('div').querySelectorAll ? qsaWorkerWrap : qsaWorkerShim;
})();
IE6/7浏览器兼容querySelectorAll、 querySelector