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I'm trying to build an json/javascript interface to check emails on haveibeenpwned.

However, when trying to set the header, I get an error (in developer tools):

jquery-1.10.2.js:8699 Refused to set unsafe header "User-Agent"

This is my code:

 $(document).ready(function() {
    $.ajax({
      url: 'https://haveibeenpwned.com/api/v2/breachedaccount/mark@fixitks.co.uk',
      type: 'GET',
      dataType: 'json',
      success: function() { alert('hello!'); },
      error: function() { alert('boo!'); }
      headers: {
  'User-Agent': 'uaheader'
I can run similar code from C# in the browser without any issues, but not in Javascript.
Is there anyway around this.
Thanks, Mark
                thanks - can I do it from just Javascript in that case, if I don't use ajax - or would that be restricted too?
– Mark Tait
                Feb 22, 2019 at 13:34
                ajax is javascript - jquery is just wrapping that. theres nothing you can do directly from the browser
– Daniel A. White
                Feb 22, 2019 at 13:35
                ... or rather directly from JS. You can override the userAgent string in Chrome's dev tools, in FF you've to set it in about: configurations.
– Teemu
                Feb 22, 2019 at 13:36
There are number of forbidden headers for setRequestHeader method. You can check here
This doc also says,
  
Note: The User-Agent header is no longer forbidden, as per spec — see
  forbidden header name list (this was implemented in Firefox 43) — it
  can now be set in a Fetch Headers object, or via XHR
  setRequestHeader().
So if you run it from Firefox 43+, it will not show Refused to set unsafe header "User-Agent" 
You will not face this problem if you make the request from your server
        
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