if (window.getSelection) {//一般浏览器
    userSelection = window.getSelection();
} else if (document.selection) {
    //IE浏览器、Opera
    userSelection = document.selection.createRange();
}
var strInput="";
try{

strInput+=" "+userSelection.toString();

}catch(e){//I兼容IE

strInput+=" "+userSelection.text;

}

谷歌中对象

IE中对象