Send POST data using XMLHttpRequest

Question

I\'d like to send some data using an XMLHttpRequest in JavaScript.

Say I have the following form in HTML:

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Answer 1

There's some duplicates that touch on this, and nobody really expounds on it. I'll borrow the accepted answer example to illustrate

http.open('POST', url, true);
http.send('lorem=ipsum&name=binny');

I oversimplified this (I use http.onload(function() {}) instead of that answer's older methodology) for the sake of illustration. If you use this as-is, you'll find your server is probably interpreting the POST body as a string and not actual key=value parameters (i.e. PHP won't show any $_POST variables). You must pass the form header in to get that, and do that before http.send()

http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');

If you're using JSON and not URL-encoded data, pass application/json instead