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我正在尝试做一些 OO JavaScript 来简单地用淡入淡出转换交换图片,但是当页面加载时没有任何反应。

我所有的图像都命名为 Joe_#.jpg,其中 # 是一个数字。

这是我的 imagesJS.js 文件:

//GLOBALS
var delay = 5000;
var opacityDelay = 100;
var pathBeginning = "images\joe\Joe_";
var pathEnding = ".jpg";

//IMAGE CLASS
function imageObj(id, start, end, initDelay) {

    this.obj = document.getElementById(id);

    this.cur = start;
    this.start = start;
    this.end = end;

    this.initDelay = initDelay;
    this.opacity = 1;


    this.fadeIn = function() {
        if(this.opacity < 1) {
            this.opacity = this.opacity + 0.1;
            obj.style.opacity = this.opacity;
            setTimeout(this.fadeIn(), opacityDelay);
        }
    }

    this.nextImage = function() {

        if(this.cur == this.end) {
            this.cur = this.start;
        }
        else {
            this.cur++;
        }

        obj.src = pathBeginning + this.cur.toString() + pathEnding;

        this.fadeIn();
    }

    this.fadeOut = function() {
        if(this.opacity > 0.5) {
            this.opacity = this.opacity - 0.1;
            obj.style.opacity = this.opacity;
            setTimeout(this.fadeOut(), opacityDelay);
        }
        else {
            this.nextImage();
        }
    }

    this.process = function() {
        setInterval(this.fadeOut(), delay + Math.floor(Math.random()*delay));
    }
}

imageObj.prototype.startProcess = function() {
    setTimeout(this.process(), this.initDelay);
}


//IMAGE OBJECTS
var img1 = imageObj('img1', 1, 5, 5000);
img1.startProcess();

以下是我如何在 HTML 页面上包含所有内容:

<head>
    <!-- Links/Scripts -->
    <link rel="stylesheet" type="text/css" href="style.css"/>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <script src="myJavascript.js" type="text/javascript"></script>
    <script src="imagesJS.js" type="text/javascript"></script>

这是 myJavascript.js 文件(可能与它有关):

// GLOBAL VARIABLES
var body = $('.body');

//***********//
//  On Load  //
//***********//
$(document).ready(function(){
    //MenuItem Color Change
    $('.menuItem').mouseover(function(){
        $(this).css({"color":"#6699ff"})
    }).mouseout(function(){
        $(this).css({"color":"black"})
    });
});

我应该将对象放在 onLoad 函数中吗?我似乎找不到我的问题。提前致谢!

//############################################### ############################ 更新1

这是更正下面 net.uk.sweet 的建议和此链接中的一些范围问题后的代码Using setTimeout() within a JavaScript class function

更新代码 -

//GLOBALS
var delay = 5000;
var opacityDelay = 100;
var pathBeginning = "images\joe\Joe_";
var pathEnding = ".jpg";

//IMAGE CLASS
function imageObj(id, start, end, initDelay) {

    this.obj = document.getElementById(id);

    this.cur = start;
    this.start = start;
    this.end = end;

    this.initDelay = initDelay;
    this.opacity = 1;


    this.fadeIn = function() {
        if(this.opacity < 1) {
            this.opacity = this.opacity + 0.1;
            this.obj.style.opacity = this.opacity;
            setTimeout(fadeIn, opacityDelay);
        }
    }

    this.nextImage = function() {

        if(this.cur == this.end) {
            this.cur = this.start;
        }
        else {
            this.cur++;
        }

        this.obj.src = pathBeginning + this.cur.toString() + pathEnding;

        this.fadeIn();
    }

    this.fadeOut = function() {
        if(this.opacity > 0.5) {
            this.opacity = this.opacity - 0.1;
            this.obj.style.opacity = this.opacity;
            setTimeout(fadeOut, opacityDelay);
        }
        else {
            this.nextImage();
        }
    }

    this.process = function() {
        var self = this;
        self.fadeOut();
        setInterval(function() {self.fadeOut();}, delay+Math.floor(Math.random()*delay));
    }
}

imageObj.prototype.startProcess = function() {
    var self = this;
    setTimeout(function() {self.process();}, this.initDelay);
}

//IMAGE OBJECTS
var img1 = new imageObj('img1', 1, 5, 5000);
img1.startProcess();

不幸的是,它仍然不起作用....有什么想法吗?

//############################################### ############################### 解决方案更新

我必须在我的其他 javascript 文件的 onLoad 函数中添加 startProcess 函数的创建和调用。

这是解决方案代码:

//GLOBALS
var delay = 5000;
var opacityDelay = 100;
var pathBeginning = "images\\joe\\Joe_";
var pathEnding = ".jpg";

//IMAGE CLASS
function imageObj(id, start, end, initDelay) {

    this.obj = document.getElementById(id);
    this.cur = start;
    this.start = start;
    this.end = end;
    this.initDelay = initDelay;
    this.opacity = 1;

    this.fadeIn = function() {
        var self = this;
        if(this.opacity < 1) {
            this.opacity = this.opacity + 0.1;
            this.obj.style.opacity = this.opacity;
            setTimeout(function() {self.fadeIn();}, opacityDelay);
        }
    }

    this.nextImage = function() {

        if(this.cur == this.end) {
            this.cur = this.start;
        }
        else {
            this.cur++;
        }

        this.obj.src = pathBeginning + this.cur.toString() + pathEnding;
        this.fadeIn();
    }

    this.fadeOut = function() {
        var self = this;
        if(this.opacity > 0.2) {
            this.opacity = this.opacity - 0.1;
            this.obj.style.opacity = this.opacity;
            setTimeout(function() {self.fadeOut();}, opacityDelay);
        }
        else {
            self.nextImage();
        }
    }

    this.process = function() {
        var self = this;
        self.fadeOut();
        setInterval(function() {self.fadeOut();}, delay + Math.floor(Math.random()*delay));
    }
}

imageObj.prototype.startProcess = function() {
    var self = this;
    setTimeout(function() {self.process();}, this.initDelay);
}

感谢所有帮助 net.uk.sweet !!!学到了很多关于范围和 chrome 开发工具的知识!希望有一天我能帮助别人!

4

1 回答 1

2

如果您熟悉您最喜欢的浏览器中的调试工具(这里是如何),那么您将帮自己一个很大的忙。控制台将输出代码中任何错误的详细信息以及您输入的任何日志语句,以帮助您跟踪程序的流程,并且您可以使用断点等高级调试功能来单步执行代码并查看代码出现故障的位置。

也就是说,我可以看到您的代码存在一些明显的问题。

在 JavaScript 中使用函数定义实例化新对象时,需要使用new关键字:

var img1 = new imageObj('img1', 1, 5, 5000);

每次使用时,setTimeout您都是直接调用该函数,而不是通过引用传递它。这意味着该函数会立即执行,而不是在超时完成时执行。例如,您应该更新 startProcess 方法中的代码,如下所示:

// Note the missing parenthesis. You should pass the function to 
// setTimeout by reference instead of invoking the function directly.
setTimeout(this.process, this.initDelay);

但是......您在使用时也会遇到与范围相关的问题(请参阅this stackoverflow threadsetTimeout上的答案以获得很好的解释)。尝试使用闭包来确保以实例为范围而不是全局窗口对象来调用您的方法:

imageObj.prototype.startProcess = function() {
    var self = this;
    setTimeout(function() {
        self.process();
    }, this.initDelay);
}

我认为该obj变量超出了您引用它的范围。尝试使用以下方法访问它:

this.fadeIn = function() {

    // Sending information to the console is a very simple way of debugging
    // your program. You can even use it to trace the value of variables! 
    console.log('In here! Current image opacity is:', this.opacity);

    if(this.opacity < 1) {
        this.opacity = this.opacity + 0.1;
        this.obj.style.opacity = this.opacity;
        setTimeout(this.fadeIn(), opacityDelay);
    }
}
于 2013-09-27T22:52:37.690 回答