input双击可以编辑，单击后还原不可编辑状态

<style>
div {border:1px #000 solid; width:120px}
</style>
<script>
window.onload = function(){
document.getElementById("azhi").ondblclick=function(){toInput(this)}
}
toInput = function(obj){
var o = document.createElement("input");
o.value = obj.innerHTML;
o.onblur=function(){toDiv(o)}
document.body.replaceChild(o, obj);
}
toDiv = function(obj){
var oDiv = document.createElement("div");
oDiv.innerHTML = obj.value;
oDiv.id = 'azhi';
oDiv.ondblclick=function(){toInput(oDiv)}
document.body.replaceChild(oDiv, obj);
}
</script>
<div id="azhi">corange</div>