Access-Control-Allow-Origin' header is present on the requested resource - angularjs

Question

I am trying to login using google authentication using node.js, but it showing error like below.
XMLHttpRequest cannot load https://accounts.google.com/o/oauth2/v2/auth?response_type=code&redirect_ur…d=410427634474-u3tpasmj4r80s6v20o54s85fikhotl79.apps.googleusercontent.com. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.
Someone please help me to solve this, because i am trying this from past two days, still didn't fix.

Answer 1

Try adding the following middleware to your NodeJS/Express app (I have added some comments for your convenience):
// Add headers
app.use(function (req, res, next) {
// Website you wish to allow to connect
res.setHeader('Access-Control-Allow-Origin', '*');
// Request methods you wish to allow
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
// Request headers you wish to allow
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
// Set to true if you need the website to include cookies in the requests sent
// to the API (e.g. in case you use sessions)
res.setHeader('Access-Control-Allow-Credentials', true);
// Pass to next layer of middleware
next();
});

Answer 2

Write this in app.get function.
res.set('Access-Control-Allow-Origin', '*');
You can use node function as
app.get("/png",function(req,res){
res.set('Access-Control-Allow-Origin', '*');
var sr = { data: "", message: "", error: "" };
console.log(222);
connection.query('SELECT * FROM png ', function(err, rows, fields) {
connection.end();
if (!err)
{
var userr = rows;
sr.data = userr;
res.json(sr);
} else{
console.log('Error while performing Query.');
}
});
});