Javascript selection的兼容性写法

 本文为大家讲解下Javascript selection的兼容性写法，感兴趣的朋友可以参考下

 代码如下:
function getSelectedText() { //this function code is borrowed from: http://www.codetoad.com/javascript_get_selected_text.asp 
 
var txt = ""; 
if (window.getSelection) { 
txt = window.getSelection(); 
} else if (window.document.getSelection) { 
txt = window.document.getSelection(); 
} else if (window.document.selection) { 
txt = window.document.selection.createRange().text; 
} 
return txt; 
}