自己写 document.ready

document.ready.js

(function () {
    var ie  = !!(window.attachEvent && !window.opera);
    var wk  = /webkit\/(\d+)/i.test(navigator.userAgent) && (RegExp.$1 < 525);
    var fn  = [];
    var run = function () { for (var i = 0; i < fn.length; i++) fn[i](); };
    var d   = document;
    d.ready = function (f) {
        if (!ie && !wk && d.addEventListener)
            return d.addEventListener('DOMContentLoaded', f, false);
        if (fn.push(f) > 1) return;
        if (ie) {
            (function () {
            try { d.documentElement.doScroll('left'); run(); }
            catch (err) { setTimeout(arguments.callee, 0); }
            })();
        } else if (wk) {
            var t = setInterval(function () {
            if (/^(loaded|complete)$/.test(d.readyState))
            clearInterval(t), run();
            }, 0);
        }
    };
})();

/*
 * How to use it
 */
document.ready(function() {
    
});