光标的设置方法

用div的contenteditable = 

function set_focus(el) {  

el=el[0];  // jquery 对象转dom对象  
el.focus();  

if($.browser.msie){  

//上面是ie的写法

var rng;  
el.focus();  
rng = document.selection.createRange(); 

rng.moveStart('character', -el.innerText.length);  

var text = rng.text;  

for (var i = 0; i < el.innerText.length; i++) {  

if (el.innerText.substring(0, i + 1) == text.substring(text.length - i - 1, text.length)) {  
result = i + 1;  
}  
}

  }else{
   
var range = document.createRange();  
range.selectNodeContents(el);  

range.collapse(false);  

var sel = window.getSelection();  
sel.removeAllRanges();  
sel.addRange(range);  


}  
}