IE 8 想用ES5 ES6的一些JS方法 需要做一些兼容

1. 兼容array.forEach

 if (!Array.prototype.forEach && typeof Array.prototype.forEach !=="function") {
   Array.prototype.forEach=function(callback, context) {
         if (Object.prototype.toString.call(this)==="[object Array]") {
             var i,
             len;
             for (i=0, len=this.length;
             i < len;
             i++) {
                 if (typeof callback==="function" && Object.prototype.hasOwnProperty.call(this, i)) {
                     if (callback.call(context, this[i], i, this)===false) {
                         break; // or return;
                     }
                 }
             }
        }
    }
}

2. 兼容node.getElementsByClassName

function getElementByClassName(node, className) {
    if (node.getElementsByClassName) {
        return node.getElementsByClassName(className);
    } else {
        var resultArr = [];
        var eles = document.getElementsByTagName("*");
        for (var iEle = 0; iEle < eles.length; iEle++) {
            var clsName = eles[iEle].getAttribute("class");
            if (clsName == className) {
                resultArr.push(eles[iEle]);
            }
        }
        return resultArr;
    }
}