ie constructor bug.js

/* MODIFY PROTOTYPE */
var _fn=function(){};
_fn.prototype.a=1;
var v=new _fn();

alert(v.a === 1); /* true */
alert(v.constructor === _fn); /* true */


/* REPLACE PROTOTYPE */
var _fn=function(){};
_fn.prototype={a:1};
var v=new _fn();

alert(v.a === 1); /* true */
alert(v.constructor === _fn); /* false in ie; true in other browsers */
/* but */
alert(v.constructor === Object.prototype); /* true in ie. ie set 'constructor' property eq Object if 'prototype' replaced */

/* REPLACE PROTOTYPE WITH FIXING BUG OF IE */
var _fn=function(){};
_fn.prototype={a:1};
var v=new _fn();
v.constructor=_fn; /* set 'constructor' property by hands */

alert(v.a === 1); /* true */
alert(v.constructor === _fn); /* now true in all browsers */