本章讲解,如何异步加载javascript文件
使用方法：
(function() {
__safeLoadScript("http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js", function() {
alert(jQuery);
});
})();
JavaScript实现代码：
window.__safeLoadScript = function(src, callback) {
function addEvent(obj, type, fn) {
if (obj.attachEvent) {
obj['e' + type + fn] = fn;
obj[type + fn] = function() { obj['e' + type + fn](window.event); }
obj.attachEvent('on' + type, obj[type + fn]);
} else
obj.addEventListener(type, fn, false);
}
function async_load(src, callback) {
var s = document.createElement('script');
s.type = 'text/javascript';
s.async = true;
var protocol = (("https:" == document.location.protocol) ? "https://" : "http://");
s.src = protocol + src;
var x = document.getElementsByTagName('script')[0];
x.parentNode.insertBefore(s, x);
s.onload = s.onreadystatechange = function() {
if(callback && (!this.readyState || this.readyState == "loaded" || this.readyState == "complete")) {
callback();
}
};
}
addEvent(window, "load", function() {
async_load(src, callback);
});
};
