When a javascript call to REST api from site page is executed, if user has no permissions on the site, he will be asked for credentials multiple times in a browser. How can I avoid/prevent that? Code below:

function requestRestApi(endpoint, options) {
  var opts = {
    type: "GET",
    url: endpoint,
    headers: { ACCEPT: "application/json;odata=verbose" }
  return jQuery.ajax(jQuery.extend(opts, options));

requestRestApi(siteUrl + "/_api/web/currentuser?$select=LoginName")
.then(function (data) {
  var user = data.d;
  var endpoint = siteUrl + "_api/web/getList('" 
    + listServerRelatedUrl + "')/getusereffectivepermissions(@u)?@u='"
    + encodeURIComponent(user.LoginName) + "'";

  .then(function(data) {
     var userPerms = data.d.GetUserEffectivePermissions;
     var perms = new SP.BasePermissions();
     console.info("Can open=" + perms.has(SP_PERMISSIONKIND_OPEN));
  • Is this related to the Auth Type somehow? Am I misconfigured my REST request or my farm's auth? – dbardakov Jan 26 '17 at 12:10
  • I have faced the same behavior with RequestExecutor approach as well, as with JSOM too. – dbardakov Jan 26 '17 at 19:55

One potential fix could be to send an OPTIONS request before the GET. OPTIONS may be failing on 401 responses [tbc].
It it does, you simply need to check the response from the OPTIONS, and don't try to issue the GET if it failed with 401.

  • Before I read you answer, was thinking about the same. Today I had tried to execute HEAD and OPTIONS but with no luck – dbardakov Jan 26 '17 at 11:07
  • If you vote up this answer, please explain if it works for you, and in which version of SharePoint (mine on-perm 2016 is not) – dbardakov Jan 26 '17 at 17:12
  • @dbardakov What was the outcome of this for you, I have the same issue. – Batman Jun 22 '17 at 18:12
  • @Batman In case of NTLM auth there is no way browser won't ask you to enter new creds in response to 401. In case it was a call to another site collection to which user doen't have ANY perms at all. – dbardakov Jun 22 '17 at 21:40
  • 1
    I ended up changing from querying the site directly to using Search API instead. So I leave the permission handling to search and I don't get credential prompts. – Batman Jun 23 '17 at 15:21

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