JS 仿支付宝input文本输入框放大组件的实例_JavaScript

input输入的时候可以在后边显示数字放大镜

<!doctype html>
<html lang="en">
 <head>
 <meta charset="utf-8">
 <title>js 仿支付宝input文本输入框放大组件</title>
 <script src="js/jquery.min.js"></script>
 <style>
  * { margin: 0; padding: 0; border-width: 1px; }
  .parentcls {margin:5px 60px 0;}
  .js-max-input {border: solid 1px #ffd2b2; position:relative;background: #fffae5;padding: 0 10px 0 10px;font-size:20px;color: #ff4400}
  .inputelem4{ width: 300px; height: 36px; border: 1px solid #e0e0e0; padding-left: 10px; line-height: 36px; font-size: 14px; }
 </style>
 </head>
 <body>
 <div class="parentcls">
  <input type="text" class="inputelem4" autocomplete = "off" maxlength="18"/>
 </div>
  <script src="js/jq22.js"></script>
  <script>
   // 初始化
   $(function(){
   new textmagnifier({
    inputelem: '.inputelem4',
    align: 'bottom',
    splittype: [6,4,4,4]
   });
   });
  </script>
 </body>
</html>

/**
 * js 仿支付宝的文本输入框放大组件
 */ 


 function textmagnifier(options) {

  this.config = {
  
  inputelem   :  '.inputelem',  // 输入框目标元素
  parentcls   :  '.parentcls',  // 目标元素的父类
  align    :  'right',   // 对齐方式有 ['top','bottom','left','right']四种 默认为top
  splittype   :  [3,4,4],   // 拆分规则
  delimiter   :  '-'    // 分隔符可自定义
  };

  this.cache = {
   isflag : false
  };
  this.init(options);
 }

 textmagnifier.prototype = {
  
  constructor: textmagnifier,

  init: function(options) {
  this.config = $.extend(this.config,options || {});
  var self = this,
   _config = self.config,
   _cache = self.cache;
  
  self._bindenv();
  
  
  },
  /*
  * 在body后动态添加html内容
  * @method _appendhtml
  */
  _appendhtml: function($this,value) {
   var self = this,
    _config = self.config,
    _cache = self.cache;

   var html = '',
    $parent = $($this).closest(_config.parentcls);

    if($('.js-max-input',$parent).length == 0) {
    html += '<div class="js-max-input"></div>';
    $($parent).append(html);
    }
    var value = self._formatstr(value);
    $('.js-max-input',$parent).html(value);
  },
  /*
  * 给目标元素定位
  * @method _position
  * @param target
  */
  _position: function(target){
  var self = this,
   _config = self.config;
  var elemwidth = $(target).outerwidth(),
   elemheight = $(target).outerheight(),
   elemparent = $(target).closest(_config.parentcls),
   containerheight = $('.js-max-input',elemparent).outerheight(); 
  
  $(elemparent).css({"position":'relative'});
  
  switch(true){
   
   case _config.align == 'top':
    
    $('.js-max-input',elemparent).css({'position':'absolute','top' :-elemheight - containerheight/2,'left':0});
    break;
   
   case _config.align == 'left':

    $('.js-max-input',elemparent).css({'position':'absolute','top' :0,'left':0});
    break;
   
   case _config.align == 'bottom':

    $('.js-max-input',elemparent).css({'position':'absolute','top' :elemheight + 4 + 'px','left':0});
    break;
   
   case _config.align == 'right':

    $('.js-max-input',elemparent).css({'position':'absolute','top' :0,'left':elemwidth + 2 + 'px'});
    break;
  }
  },
  /**
  * 绑定事件
  * @method _bindenv
  */
  _bindenv: function(){
  var self = this,
   _config = self.config,
   _cache = self.cache;

  // 实时监听输入框值的变化
  $(_config.inputelem).each(function(index,item){

   $(item).keyup(function(e){
    var value = $.trim(e.target.value),
     parent = $(this).closest(_config.parentcls);
    if(value == '') {
     self._hide(parent);
    }else {

     var html = $.trim($('.js-max-input',parent).html());

     if(html != '') {
      self._show(parent);
     }
    }
    self._appendhtml($(this),value);
    self._position($(this));
   });

   $(item).unbind('focusin');
   $(item).bind('focusin',function(){
    var parent = $(this).closest(_config.parentcls),
     html = $.trim($('.js-max-input',parent).html());

    if(html != '') {
     self._show(parent);
    }
   });

   $(item).unbind('focusout');
   $(item).bind('focusout',function(){
    var parent = $(this).closest(_config.parentcls);
    self._hide(parent);
   });
  });
  },
  /**
  * 格式化下
  * @method _formatstr
  */
  _formatstr: function(str){
  var self = this,
   _config = self.config,
   _cache = self.cache;
  var count = 0,
   output = [];
  for(var i = 0, ilen = _config.splittype.length; i < ilen; i++){
   var s = str.substr(count,_config.splittype[i]);
   if(s.length > 0){
    output.push(s);
   }
   count+= _config.splittype[i];
  }
  return output.join(_config.delimiter);
  },
  /*
  * 显示 放大容器
  * @method _show
  */
  _show: function(parent) {
  var self = this,
   _config = self.config,
   _cache = self.cache;
  if(!_cache.isflag) {
   $('.js-max-input',parent).show();
   _cache.isflag = true;
  }
  },
  /*
  * 隐藏 放大容器
  * @method hide
  * {public}
  */
  _hide: function(parent) {
  var self = this,
   _config = self.config,
   _cache = self.cache;
  if(_cache.isflag) {
   $('.js-max-input',parent).hide();
   _cache.isflag = false;
  }
  }
 };

效果图