OO Javascript调试 - 使用转换进行图像交换

时间:2013-09-27 20:15:30

标签: javascript jquery html image oop

我正在尝试使用一些OO JavaScript只是简单地用淡入淡出过渡交换图片,但是当页面加载时没有任何反应。

我的所有图像都被命名​​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();

以下是我在HTML页面中包含所有内容的方法:

<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(也许它与它有关):

// 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?我似乎无法找到我的问题。 在此先感谢!

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

以下是纠正以下net.uk.sweet建议后的代码以及此链接中的一些范围问题Using setTimeout() within a JavaScript class function

更新的代码 -

//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....任何想法?

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

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

以下是解决方案代码:

//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 dev工具的知识! 希望有一天我可以帮助别人!

1 个答案:

答案 0 :(得分:2)

如果您熟悉自己喜欢的浏览器中的调试工具(here's how),那么您将会受益匪浅。控制台将输出代码中的任何错误的详细信息以及您输入的任何日志语句,以帮助您遵循程序流程,并且您可以使用高级调试功能(如断点)来逐步执行代码并查看其中断的位置。

那就是说,我可以看到你的代码有一些明显的问题。

使用函数定义在JavaScript中实例化新对象时,需要使用new关键字:

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

每次使用setTimeout时,您都会直接调用该函数,而不是通过引用传递它。这意味着该功能立即执行,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......在使用setTimeout时,您也遇到了与范围相关的问题(请参阅this stackoverflow thread上的答案以获得详细解释)。尝试使用闭包来确保使用实例作为范围而不是全局窗口对象来调用方法:

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

我认为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);
    }
}