why xhr cannot set response type when async is false

Question

var xhr = new XMLHttpRequest();

xhr.responseType = 'json';

xhr.open('GET', '/api/album/category', false);

//ERROR: VM829:1 Uncaught DOMException: Failed to execute 'open' on 'XMLHttpRequest': Synchronous requests from a document must not set a response type.at :1:5(anonymous function) @ VM829:1

why xhr cannot set response type when async is false?????

Because SJAX is bad and shouldn't be used anyway. It's limited to the most simple use cases, and does not support response types, CORS, etc. — Bergi, Nov 08 '16 at 12:06

score 0 · Accepted Answer · answered Nov 08 '16 at 10:58

0

You cannot set the response type when the synchronous flag is set (i.e, asynch is false) . It will throw an "InvalidAccessError" exception . Refer https://xhr.spec.whatwg.org/#the-responsetype-attribute

answered Nov 08 '16 at 10:58

Gokul Govindaraju

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why xhr cannot set response type when async is false

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