placeholder兼容各浏览器

var funPlacegholder = function(element){
    //检测浏览器是否支持placeholder
    var placeholder = '';
    if(element && !('placeholder' in document.createElement('input')) && (placeholder = element.getAttribute('placeholder'))) {
        //当前控件是否有id，没有则创建
           //个人感觉这里不需判断id

        var idLabel = element.id;
        if(idLabel){
            idLabel = 'placeholder' + new Date().getTime();
            element.id = idLabel;
        }
        
        //创建label元素
        var eleLabel = document.createElement("label");
        eleLabel.htmlFor = idLabel;
        eleLabel.style.position = "absolute";
        eleLabel.style.color = 'graytext';
        eleLabel.style.cursor = "text";
        //插入创建的label元素节点
        element.parentNode.insertBefore(eleLabel,element);
        //事件
        element.onfocus = function(){
            eleLabel.innerHTML = '';
        };
        
        element.onblur = function(){
            if(this.value === ""){
               eleLabel.innerHTML = placeholder;
            }
        };
        
        //样式初始化
        if(element.value === ""){
            eleLabel.innerHTML = placeholder;
        }
    }
};

 

参考：张鑫旭：HTML5 placeholder实际应用经验分享及拓展