无休止的javascript函数原型
无休止的javascript函数原型
提问于 2013-01-26 02:23:18
我正在尝试创建一个无尽的原型函数。这是我的尝试，它不起作用：
function Cat(name, direction) {
this.name = name;
this.stand = {left: "images/standLeft.png", right: "images/standRight.png"};
this.walk = {left: "images/walkLeft.gif", right: "images/walkRight.gif"};
this.direction = direction;
}
Cat.prototype.walking = function() {
var myDirection = (this.direction == "right" ? "+=": "-=");
var myPosition = $("#cat").css("left");
myPosition = myPosition.substring(0, myPosition.length - 2);
var distanceLeft = myPosition;
var distanceRight = 1024 - myPosition - 173;
if(this.direction == "right") {
var distance = distanceRight;
} else {
var distance = distanceLeft;
}
$("#cat img")[0].src = this.walk[this.direction];
$("#cat").animate({
left: myDirection + distance
}, (22.85 * distance), function(){
this.direction = (this.direction == "right" ? "left": "right");
this.walking();
});
}
var myCat = new Cat("Izzy", "right");我以为调用(this.walking())会用相同的对象再次运行相同的函数，但是它抛出了一个错误。有什么想法或建议吗？
回答 2
Stack Overflow用户
回答已采纳
发布于 2013-01-26 02:27:10
this将会有窗口作用域。
$("#cat img")[0].src = this.walk[this.direction];
var that = this;
$("#cat").animate({
left: myDirection + distance
}, (22.85 * distance), function(){
that.direction = (that.direction == "right" ? "left": "right");
that.walking();
});Stack Overflow用户
发布于 2013-01-26 02:47:58
请参阅我在this StackOvervlow thread上对JavaScript (和jQuery)中的作用域处理的解释。在您的情况下，您应该接受jQuery将选择this作为您的cat对象以外的对象。还要注意，jQuery使用的是HTML元素，而不是cat的实例，所以即使它想要这样做，也不能设置this = your对象。
您可以通过将函数包装在$.proxy (link)中来缓解此问题，如下所示：
// This is your original handler. I made this a named function for clarity.
var animateHandler = function() {
this.direction = (this.direction == "right" ? "left": "right");
this.walking();
}
// Now here's your original call to animate.
$("#cat").animate(
{ left: myDirection + distance},
(22.85 * distance),
animateHandler
);
// Here's what you'd change it to.
$("#cat").animate(
{ left: myDirection + distance },
(22.85 * distance),
$.proxy(animateHandler, this)
);页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/14528034
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