网页加载后覆盖现有的javascript方法-应该可以吗？

Question

I have a page which uses various internal corporate javascript files for some functionality. These files are minified before we include them on the page.

After the page loads, in the browser javascript console, I can add methods to the existing internal javascript objects like so : MyCompany.CompanyObject.newMethod = function(){...} and that appears to work fine.

Overwriting an existing method isn't working so well. If I do MyCompany.CompanyObject.existingMethod = function(){...} that appears to take hold, but when we actually call existingMethod it's using the old definition, as defined in our minified javascript files.

If I set a breakpoint on our minified javascript file where existingMethod lives and (say) fire a jQuery click event on a DOM element to trigger it, the breakpoint stops on the old method definition-- which makes sense, since that's what's in the minified file.

But should that be happening, given that I redefined existingMethod after the page loaded? We're not reloading the page after I redefine the method, so it shouldn't be the case my new definition was wiped out.

I think what I'm doing is possible, and it could be something odd is happening in my specific case, but wanted to see if what I'm trying to do is possible? Any chance there's some strange source caching going on when trying this in a browser console?

Answer 1

When you overwrite the existing method, you are not changing the method itself, but only the reference to the method and making it point to the new method (so now there are two methods in the memory).

If the code passes a reference to the old method to someone else (say by setting it as an event-handler) then the old method will continue to be called.

You should look at the stack-trace to see who is calling the old method, and then try to figure out where they got the reference from.