In this post I’m going to demonstrate a CORS Wrapper for postMessage operations, specifically in SharePoint, and intended to make CORS operations as simple as the Ajax operations we’re more familiar with. I’m going to develop the same simple pages I used in my last post, only using the CORS Wrapper this time. Then I’ll dump the CORS Wrapper on you. I’m not going to talk a great deal about the code, I’ve included a ridiculous number of comments in the code to explain what I’m doing.
And yet, in my experience, a lot of developers think this is too complicated and don’t want to deal with it. I think the reasons for this are twofold:
- SharePoint and it’s web services are already complicated. First, there’s a bunch of them, and they all take different parameters. And you need to set different headers depending on what you’re doing. And is it a GET, or POST, or MERGE. And they’re not very well documented, although that’s getting better. There are plenty of simple examples, but few complex ones (for instance, a lot is left to the imagination when it comes to filters or how lazy loading works).
- While postMessage does not add a ton of complexity, adding any complexity at all makes developers groan in agony (mostly because of reason 1).
Looks like an opportunity for some sort of CORS Wrapper or library. Deal with the complexity once, and forever more use the library to hide most if not all of the additional complexity.