无法获取隐藏元素宽度和高度的解决方案

在实际开发中会遇到确实需要获取隐藏元素的宽高，这儿所说的隐藏元素是display为none的元素。

可使用jQuery Actual Plugin插件来完成，其源码如下：

;( function ( $ ){
 $.fn.addBack = $.fn.addBack || $.fn.andSelf;
 $.fn.extend({
  actual : function ( method, options ){
   // check if the jQuery method exist
   if( !this[ method ]){
    throw '$.actual => The jQuery method "' + method + '" you called does not exist';
   }
   var defaults = {
    absolute   : false,
    clone     : false,
    includeMargin : false,
    display    : 'block'
   };
   var configs = $.extend( defaults, options );
   var $target = this.eq( 0 );
   var fix, restore;
   if( configs.clone === true ){
    fix = function (){
     var style = 'position: absolute !important; top: -1000 !important; ';
     // this is useful with css3pie
     $target = $target.
      clone().
      attr( 'style', style ).
      appendTo( 'body' );
    };
    restore = function (){
     // remove DOM element after getting the width
     $target.remove();
    };
   }else{
    var tmp  = [];
    var style = '';
    var $hidden;
    fix = function (){
     // get all hidden parents
     $hidden = $target.parents().addBack().filter( ':hidden' );
     style  += 'visibility: hidden !important; display: ' + configs.display + ' !important; ';
     if( configs.absolute === true ) style += 'position: absolute !important; ';
     // save the origin style props
     // set the hidden el css to be got the actual value later
     $hidden.each( function (){
      // Save original style. If no style was set, attr() returns undefined
      var $this   = $( this );
      var thisStyle = $this.attr( 'style' );
      tmp.push( thisStyle );
      // Retain as much of the original style as possible, if there is one
      $this.attr( 'style', thisStyle ? thisStyle + ';' + style : style );
     });
    };
    restore = function (){
     // restore origin style values
     $hidden.each( function ( i ){
      var $this = $( this );
      var _tmp = tmp[ i ];

      if( _tmp === undefined ){
       $this.removeAttr( 'style' );
      }else{
       $this.attr( 'style', _tmp );
      }
     });
    };
   }
   fix();
   // get the actual value with user specific methed
   // it can be 'width', 'height', 'outerWidth', 'innerWidth'... etc
   // configs.includeMargin only works for 'outerWidth' and 'outerHeight'
   var actual = /(outer)/.test( method ) ?
    $target[ method ]( configs.includeMargin ) :
    $target[ method ]();
   restore();
   // IMPORTANT, this plugin only return the value of the first element
   return actual;
  }
 });
})(jQuery);

当然如果要支持模块化开发，直接使用官网下载的文件即可，源码也贴上：

;( function ( factory ) {
if ( typeof define === 'function' && define.amd ) {
  // AMD. Register module depending on jQuery using requirejs define.
  define( ['jquery'], factory );
} else {
  // No AMD.
  factory( jQuery );
}
}( function ( $ ){
 $.fn.addBack = $.fn.addBack || $.fn.andSelf;
 $.fn.extend({
  actual : function ( method, options ){
   // check if the jQuery method exist
   if( !this[ method ]){
    throw '$.actual => The jQuery method "' + method + '" you called does not exist';
   }
   var defaults = {
    absolute   : false,
    clone     : false,
    includeMargin : false,
    display    : 'block'
   };
   var configs = $.extend( defaults, options );
   var $target = this.eq( 0 );
   var fix, restore;
   if( configs.clone === true ){
    fix = function (){
     var style = 'position: absolute !important; top: -1000 !important; ';
     // this is useful with css3pie
     $target = $target.
      clone().
      attr( 'style', style ).
      appendTo( 'body' );
    };
    restore = function (){
     // remove DOM element after getting the width
     $target.remove();
    };
   }else{
    var tmp  = [];
    var style = '';
    var $hidden;
    fix = function (){
     // get all hidden parents
     $hidden = $target.parents().addBack().filter( ':hidden' );
     style  += 'visibility: hidden !important; display: ' + configs.display + ' !important; ';
     if( configs.absolute === true ) style += 'position: absolute !important; ';
     // save the origin style props
     // set the hidden el css to be got the actual value later
     $hidden.each( function (){
      // Save original style. If no style was set, attr() returns undefined
      var $this   = $( this );
      var thisStyle = $this.attr( 'style' );
      tmp.push( thisStyle );
      // Retain as much of the original style as possible, if there is one
      $this.attr( 'style', thisStyle ? thisStyle + ';' + style : style );
     });
    };
    restore = function (){
     // restore origin style values
     $hidden.each( function ( i ){
      var $this = $( this );
      var _tmp = tmp[ i ];

      if( _tmp === undefined ){
       $this.removeAttr( 'style' );
      }else{
       $this.attr( 'style', _tmp );
      }
     });
    };
   }
   fix();
   // get the actual value with user specific methed
   // it can be 'width', 'height', 'outerWidth', 'innerWidth'... etc
   // configs.includeMargin only works for 'outerWidth' and 'outerHeight'
   var actual = /(outer)/.test( method ) ?
    $target[ method ]( configs.includeMargin ) :
    $target[ method ]();
   restore();
   // IMPORTANT, this plugin only return the value of the first element
   return actual;
  }
 });
}));

代码实例：

//get hidden element actual width
$('.hidden').actual('width');
//get hidden element actual innerWidth
$('.hidden').actual('innerWidth');
//get hidden element actual outerWidth
$('.hidden').actual('outerWidth');
//get hidden element actual outerWidth and set the `includeMargin` argument
$('.hidden').actual('outerWidth',{includeMargin:true});
//get hidden element actual height
$('.hidden').actual('height');
//get hidden element actual innerHeight
$('.hidden').actual('innerHeight');
//get hidden element actual outerHeight
$('.hidden').actual('outerHeight');
// get hidden element actual outerHeight and set the `includeMargin` argument
$('.hidden').actual('outerHeight',{includeMargin:true});
//if the page jumps or blinks, pass a attribute '{ absolute : true }'
//be very careful, you might get a wrong result depends on how you makrup your html and css
$('.hidden').actual('height',{absolute:true});
// if you use css3pie with a float element
// for example a rounded corner navigation menu you can also try to pass a attribute '{ clone : true }'
// please see demo/css3pie in action
$('.hidden').actual('width',{clone:true});

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