Javascript selection的兼容性写法介绍

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; 
}