switch theme in javascript -

I try to switch to my subjects ... but it does not work. I want a default style (when I open the page), and I want to switch from

, but I try it but it does not work:

 < Code> & lt; Link rel = "stylesheet" type = "text / css" href = "script / easyi / theme / dark / easy types? V = 20130 9 13" />   
 This is the topic for changing and changing:  
    
 and my switch:  
  & lt; Form action = "#" action = "post" & gt; & Lt; Select name = "select_box_chosen_color" id = "select_box_chosen_color" & gt; & Lt; Option value = "blue" & gt; Blue & lt; / Options & gt; & Lt; Option value = "orange" & gt; Yellow & lt; / Options & gt; & Lt; / Select & gt; & Lt; Input type = "submit" & gt; & Lt; / Form & gt;    
 
 
 option 1: a CSS file  
  value You need to use the jQuery   
 only for the  change  on your  select , change the CSS class into body Tag  
  var theme = $ ('# select_box_chosen_color'); Theme.change (function () {$ (document.body) .prop ("class", $ (this) .find (": selected"). Val ());}) Change (); // Optional trigger ollods   
 In CSS, you use the theme chosen as a major class to overwrite the theme:  
 . MyDefault {color: green; } .blue. MyDefault {color: blue; }   
 Option 2: Multiple CSS files  
  Assume that you are developing on a  http: //  server If you want to change the file, click on the  file: //  system   on the  link  tag of the id or data attribute Use  
  HTML   
  & lt; Link id = "themeLink" href = "script / easy / theme / dark / easy types? V = 20130913" Rel = "stylesheet" type = "text / css" />   
 The options can hold directory structure.  
  & lt; ID = "Theme Options" & gt; & Lt; Option value = "" & gt; Default & lt; / Option & gt; & Lt; Option value = "blue" & gt; Blue & lt; / Options & gt; & Lt; / Select & gt; Depending on your directory structure, you should create a directory root related to your URL  / . Insert with value from   
  JS   and  select  options will reload the most modern browser urls, if it Created correctly without problem.  
  var option = $ ('# Theme Options'), dir =' script / easyui / themes / ', file =' Easyui.css? V = ', link = $ (' #meamelink '); Options.change (function () {var selected = $ (this) .find (': selected'). Val (), time = new date (). GetTime (); // Optionally to avoid caching files Time includes = selected .length? '/' + File: file; link.prop ('href', dir + selected + file + time);}). Change (); // Alternate trigger load   
 I've heard some tools / browsers and combinations with  iframe  did not reload the style properly. For this you should see a dynamic creation of a  link  tag technology.  
 Wrap your script functionality inside a DOM ready event.