先看效果图：

要求：当输入框获得焦点时，自动显示验证图片。

代码如下（学习而已，仅供参考）：

复制代码 代码如下:

/***********************下是验证码对象*****************/

var Validation = {};

Validation.init = function(eleName,imageSrc){

this.image = imageSrc;

$('#'+eleName).focusin(function(){

Validation.show(eleName);

});

}

Validation.image = '';

Validation.display=false;

Validation.width = '100px';

Validation.height = '30px';

Validation.div = null;

Validation.show = function(eleName){

if(this.display==false){

//首次显示

if(this.div==null){

$('#'+eleName).after('<div id="div_validation_'+eleName+'" title="点击更换"></div>');

this.div = $('#div_validation_'+eleName);

this.div.css('position','absolute');

this.div.css('cursor','pointer');

this.div.css('border','1px solid #CCC');

this.div.css('background-color','#FFF');

this.div.css('background-position','center');

this.div.css('background-repeat','no-repeat');

this.div.css('height',this.height);

this.div.css('width',this.width);

var objOffset = $('#'+eleName).offset();

objOffset.top+=$('#'+eleName).height()+6;

this.div.offset(objOffset);

this.div.css('background-image','url('+Validation.image+'&_t='+new Date()+')');

this.div.css('display','inline-block');

this.display = true;

//点击更换

this.div.click(function(){

Validation.div.css('background-image','url('+Validation.image+'&_t='+new Date()+')');

});

}

else{

this.div.css('background-image','url('+Validation.image+'&_t='+new Date()+')');

this.display = true;

this.div.css('display','inline-block');

}

}

}

Validation.hide =function(){

if(this.display==true){

this.display = false;

this.div.hide();

}

}

使用方式：

复制代码 代码如下:

//验证码对象初始化

Validation.init('validation','Ajax.ashx?handle=validation');

// 输入框ID 验证图片地址

//隐藏

Validation.hide();