'Access-Control-Allow-Credentials' header in the response is '' which must be 'true'

Question

I\'m using node, express on backend and angular4 at client side which is giving me following error:

XMLHttpRequest cannot load http://localhost:4876/l

Answer 1

While setting cors in corsOptions I added value credentials true it worked as follows:

private setCors(){
        let whitelist = ['http://localhost:4200','http://localhost:80'];
        let corsOptions = {
            origin: (origin:any, callback:any)=>{
                if (whitelist.indexOf(origin) !== -1) {
                    callback(null, true)
                } else {
                    callback(new Error('Not allowed by CORS'))
                }
            },credentials: true
        }
        this.app.use(cors(corsOptions));
    }