Error: Generating Access Token while calling API from External Application

Here is the code.

const http = new XMLHttpRequest();
const clId="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
const redirectpage="">community-dev.thomsonreuters.com/testRestApi.html";
const url = 'community-qa.thomsonreuters.com/.../authorize';
http.open('GET', url,true);
http.setRequestHeader("Access-Control-Allow-Origin", "*");
http.setRequestHeader('response_type', 'token');
http.setRequestHeader('redirect_uri', redirectpage);
http.setRequestHeader('client_id', clId);
http.send(null);
http.onload = ()=>{
if(http.status===200) {
debugger;
//var parm=getParams(http.responseURL);
//document.getElementById('demo').innerHTML=http.response;
} else {
console.log(`error ${http.status}`)
}
}

Hi, 

As per the above conversation its clear that you are using a grant type as code so you need to form the URL as below

http://community-qa.thomsonreuters.com//api.ashx/v2/oauth/authorize?response_type=token&client_id=placeyourclientid&redirect_uri=placeredirecturlhere

and if you type this URL directly on the browser you should see the login screen as below

And the you need to allow the application click allow on next screen

And then you should be redirected back to your return url page with the access token and Expiry time as query string parameters