[jQuery]无法准确获取隐藏元素（display:none）宽度(width)和高度(height)的新解决方案

在开发一个弹框插件时，遇到一个需要计算隐藏弹框的高度问题。用jquery里面的方法$('box').outerHeight(true)得到隐藏层高度的值随着滚动条滚动总是不一致。没辙，放弃这一方法去获取，原来生js中的offsetHeight来试试看，$(''box")[0].offsetHeight，毫无疑问得到的值总是0。

为解决这个老大难问题，在网上看到另一较好的解决方法新增扩展jquery对象原型方法actual

范例代码：

//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});

原码如下并引入：

;( 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

};

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: block !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 (){

var $this = $( this );

//
Save original style. If no style was set, attr() returns undefined

tmp.push( $this.attr( 'style' ));

$this.attr( '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 );