JS无法获取display为none的隐藏元素的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});