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）：

/***********************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 style="display:none;" 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：

//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();

以上就是本文的全部内容，希望对大家的学习有所帮助。