Hey there Javascript wizards! I've got a tricky problem on my hands and can't seem to find a solution that satisfies me.
I'm working on a specific JavaScript framework where I need to set the __proto__ property of a dynamically created function. I have a generic function factory and require consistent definitions for these functions. Let's not dwell on whether this is a good practice, as I have valid reasons for needing to do so.
Check out this QUnit example code snippet that works perfectly in the latest version of Chrome:
var oCommonFunctionProto = {};
var fnCreateFunction = function () {
var fnResult = function () {};
fnResult.__proto__ = oCommonFunctionProto; // DOES NOT WORK WITH IE9 OR IE10
return fnResult;
};
var fn1 = fnCreateFunction();
oCommonFunctionProto.randomMethod = function() { return 10; };
equal(fn1.randomMethod(), 10, "__proto__ has been set properly");
var oInstance = new fn1(); // fn1 is instantiable
In this code, anything added to oCommonFunctionProto will be directly available on any function created using the fnCreateFunction method. This allows us to build prototype chains on Function objects, similar to how it's done with object prototype chains.
The issue lies here: the __proto__ property is immutable in IE9 and IE10, and unfortunately, I need compatibility with those browsers. Additionally:
- I cannot rely on any third-party tools. I need standalone code that works independently.
- As you can see, the randomMethod was added after the function was created. I must maintain prototype chaining because in my scenarios, these objects will be modified post-function creation. Simply duplicating oCommonFunctionProto properties on the function prototype won't suffice.
- I'm okay with suboptimal code if it gets the job done. This compatibility workaround is specifically for IE9/IE10. As long as it works, I'll be satisfied.
- It might be acceptable to set the __proto__ at function creation. Although preferable to do it afterwards, if there's no alternative, then setting it during creation could be an option.
I've tried various hacks but couldn’t find a way around this restriction in IE9/IE10.
TL;DR: I need to set the __proto__ on a JavaScript function without relying on any third-party solutions in IE9 and IE10.