Is there a way to check whether the resource at a given endpoint exists before sending out a GET request?
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See [this question](https://stackoverflow.com/questions/16539269/http-head-vs-get-performance) – Bart Platak Jan 04 '16 at 20:57
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2You can send a Head request? There's no way for you to know unless you make contact with the server – Eric Guan Jan 04 '16 at 20:57
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How would I 'send a Head request'? Will that return a boolean? – Jan 04 '16 at 20:59
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1http://stackoverflow.com/questions/333634/http-head-request-in-javascript-ajax you send the request then check the response status – Paolo Jan 04 '16 at 21:05
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HEAD, but whether or not it's actually worth it depends on the resource you're requesting, really.
Or create a new request that checks for resource existence and use the results of that to determine if you should bother fetching the resource.
Dave Newton
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That's what I'm trying to get at: to determine whether I am going to fetch it in the future or not. – Jan 04 '16 at 21:03
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1@NikitaTomkevich *Going* to, or *can*? In any case, if it's a small resource, I'd just grab it. If it isn't, or you're optimizing for mobile or something, then a HEAD request is probably what you want. As to what it returns, it depends on what you're calling. For example, IIRC Rails used to handle a HEAD request as a GET so you had to check manually and use a `head` response. – Dave Newton Jan 04 '16 at 21:56
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I'm not sure why this wasn't immediately obvious to me, but after I banged my head against my keyboard for a while, pun intended, I finally figured out that HEAD was just another REST method like GET or POST. This insight might help somebody. – OCDev Apr 30 '22 at 17:27
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The only way to check if a resource is available is to try to fetch it and see if it exists.
You could cache a list and at least you wouldnt need to try twice but there is no way around it the first time.
Toby Allen
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JavaScript supports Try/Catch statements, we can give more detailed answers if specifically referenced functions or libraries are mentioned in the question.
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