JAVA高级面试进阶训练营视频教程

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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});

插件地址：http://dreamerslab.com/works