问题
Asking about Object.defineProperty as demonstrated below:
function testComponent(){
var testProperty;
Object.defineProperty(this, "testProperty",
{
get : function()
{
return testProperty;
},
set : function(val)
{
testProperty = val;
}
});
}
Where it would be used like so:
testObject = new testComponent();
testObject.testProperty = "testValue";
Based on what I've seen so far, it looks like there is no cross browser solution, as I've tried using es5-shim with no luck, but I would like to confirm. I also found a reference to this post and my tests still fail in IE 7 & 8, can anyone shed any light on this?
I remember looking through a related question a few months ago somewhere on S/O and I think I saw someone had written a solution for this in an answer. Any general workarounds for getter / setters would also be appreciated. The idea is that I need some equivalent of a getter setter on an object without passing the parameter change through a method. I don't need IE6, but I would like to support browsers in the range of IE7+ ff 3.6+ , etc
QUnit tests below: (jsFiddles)
(these pass in all browsers on my machine except IE 7 & 8
direct use of defineProperty, no shims:
http://jsfiddle.net/uSYFE/
fiddle using the ES5 shim, I'm assuming all I need to do is include it? :
http://jsfiddle.net/hyperthalamus/ntwDy/
fiddle using the IE recommended solution :
http://jsfiddle.net/hyperthalamus/xfvz3/
回答1:
According to ES5-shim:
/!\ Object.defineProperty
This method will silently fail to set "writable", "enumerable", and "configurable" properties.
Providing a getter or setter with "get" or "set" on a descriptor will silently fail on engines that lack "defineGetter" and "defineSetter", which include all versions of IE up to version 8 so far.
IE 8 provides a version of this method but it only works on DOM objects. Thus, the shim will not get installed and attempts to set "value" properties will fail silently on non-DOM objects.
https://github.com/kriskowal/es5-shim/issues#issue/5
So you know your answer. It can be done on DOM elements, that's it (and on IE8 only).
I'd suggest you just use get/set methods if you want IE7 to work.
回答2:
For older IEs you'd have to make sure your property is a dom object (even a fake tag) and use onPropertyChange to get notified. See this post by John Dyer for more details.
回答3:
I've had this same question myself. (See here.) It doesn't look like it's fully possible in IE8 or lower. Otherwise the ES5 Shim is your best bet.
来源:https://stackoverflow.com/questions/10282075/object-defineproperty-for-all-browsers