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分享关于js标签的一些疑问
代码： function b(){
btn.addEventListener('click',a,false);
}
function a(){
var btn=document.getElementById("btn");
btn.value=parseInt(btn.value)+1
}
b();
当把function a(){}改为a:function(){}就不能用了。求大神帮我解答。
btn.addEventListener('click',a,false);
}
function a(){
var btn=document.getElementById("btn");
btn.value=parseInt(btn.value)+1
}
b();
当把function a(){}改为a:function(){}就不能用了。求大神帮我解答。
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SkyGst 2016-09-22
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{a:function(){},b:function(){}} 这是函数的结构，用的是json方式。也可以称之为对象字面量。
shexm123 2016-09-21
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我是看了一个轮播代码产生的困惑
function ZoomPic ()
{
this.initialize.apply(this, arguments)
}
ZoomPic.prototype =
{
initialize : function (id)
{
var _this = this;
this.wrap = typeof id === "string" ? document.getElementById(id) : id;
this.oUl = this.wrap.getElementsByTagName("ul")[0];
this.aLi = this.wrap.getElementsByTagName("li");
this.prev = this.wrap.getElementsByTagName("span")[0];
this.next = this.wrap.getElementsByTagName("span")[1];
this.timer = 1000;
this.aSort = [];
this.iCenter = 2;
this._doPrev = function () {return _this.doPrev()};
this._doNext = function () {return _this.doNext()};
this.options = [
{width:365, height:252, top:40, left:0, zIndex:1},
{width:405, height:280, top:20, left:60, zIndex:2},
{width:445, height:308, top:0, left:130, zIndex:3},
{width:405, height:280, top:20, left:240, zIndex:2},
{width:366, height:252, top:40, left:345, zIndex:1},
];
for (var i = 0; i < this.aLi.length; i++) this.aSort[i] = this.aLi[i];
this.aSort.unshift(this.aSort.pop());
this.setUp();
this.addEvent(this.prev, "click", this._doPrev);
this.addEvent(this.next, "click", this._doNext);
this.doImgClick();
this.timer = setInterval(function ()
{
_this.doNext()
}, 3000);
this.wrap.onmouseover = function ()
{
clearInterval(_this.timer)
};
this.wrap.onmouseout = function ()
{
_this.timer = setInterval(function ()
{
_this.doNext()
}, 3000);
}
},
doPrev : function ()
{
this.aSort.unshift(this.aSort.pop());
this.setUp()
},
doNext : function ()
{
this.aSort.push(this.aSort.shift());
this.setUp()
},
doImgClick : function ()
{
var _this = this;
for (var i = 0; i < this.aSort.length; i++)
{
this.aSort[i].onclick = function ()
{
if (this.index > _this.iCenter)
{
for (var i = 0; i < this.index - _this.iCenter; i++) _this.aSort.push(_this.aSort.shift());
_this.setUp()
}
else if(this.index < _this.iCenter)
{
for (var i = 0; i < _this.iCenter - this.index; i++) _this.aSort.unshift(_this.aSort.pop());
_this.setUp()
}
}
}
},
setUp : function ()
{
var _this = this;
var i = 0;
for (i = 0; i < this.aSort.length; i++)
{
this.aSort[i].index = i;
if (i < 5)
{
this.css(this.aSort[i], "display", "block");
this.doMove(this.aSort[i], this.options[i]
)}
}
},
addEvent : function (oElement, sEventType, fnHandler)
{
return oElement.addEventListener ? oElement.addEventListener(sEventType, fnHandler, false) : oElement.attachEvent("on" + sEventType, fnHandler)
},
css : function (oElement, attr, value)
{
if (arguments.length == 2)
{
return oElement.currentStyle ? oElement.currentStyle[attr] : getComputedStyle(oElement, null)[attr]
}//oElement.currentStyle全局方法获取样式，IE浏览器获取外//部样式的实现方式为oElement.currentStyle属性。
else if (arguments.length == 3)//定义样式
{
switch (attr)
{
case "width":
case "height":
case "top":
case "left":
case "bottom":
oElement.style[attr] = value + "px";
break;
case "opacity" :
oElement.style.filter = "alpha(opacity=" + value + ")";
oElement.style.opacity = value / 100;
break;
default :
oElement.style[attr] = value;
break
}
}
},
doMove : function (oElement, oAttr, fnCallBack)
{
var _this = this;
clearInterval(oElement.timer);
oElement.timer = setInterval(function ()
{
var bStop = true;
for (var property in oAttr)//获取传入的oAttr定义的属性
{
var iCur = parseFloat(_this.css(oElement, property));
property == "opacity"&& (iCur = parseInt(iCur.toFixed(2) * 100));
/*等价于if(property == "opacity"){
iCur = parseInt(iCur.toFixed(2) * 100);}*/
var iSpeed = (oAttr[property] - iCur) / 50;
iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
if (iCur != oAttr[property])
{
bStop = false;
_this.css(oElement, property, iCur + iSpeed)
}
}
if (bStop)
{
clearInterval(oElement.timer);
fnCallBack && fnCallBack.apply(_this, arguments) //等价于if(fnCallBack) { fnCallBack.apply(_this, arguments)}
}
}, 30)
}
};
window.onload = function ()
{
new ZoomPic("focus_Box");
};
为什么addevent（）不能写成this.addEvent(this.prev, "click", doPrev);
