日期:2014-05-16 浏览次数:20349 次
function clickFun(value,elemID){ this._value = value; this._elem = document.getElementById(elemID); this._elem.ButtonFun = this;//this指向clickFun对象 this._elem.onclick = this.clickHandler;//来自与原型 } clickFun.prototype.clickHandler = function(){ //这里为什么this是指向_elem的引用,即指向document.getElementById(elemID); //因为clickHandler赋给了onclick,而onclick的调用者是_elem,所以他的执行上下文为_elem对象 //所以buttonFun是指向clickFun的引用 var buttonFun = this.ButtonFun; var value = (buttonFun && buttonFun._value) ? buttonFun._value : "unknow value"; alert("value" + value); alert("this.value" + this.value); } window.onload = function(){ new clickFun("赋给程序的值","bt"); }
<button type="button" value="我是按钮的值" id="bt">click me~</button>