Amazon S3 javascript sdk for Browser throwing 403 error

Question

I am using Amazon s3 javascript sdk for one of my applications. I am getting the following error:

XMLHttpRequest cannot load https://s3.amazonaws.com/. Response for preflight has invalid HTTP status code 403

I see that the preflight requests are failing in my case.

I am using Angular2 for my application and I am trying to get the list of buckets. This is the code I wrote:

getBuckets(comp: any) {
        var s3 = this.getS3();
        var params = {};
        s3.listBuckets(params, function(err, response) {
            if (err) {
                console.log(err);
                console.log('error from list buckets');
            }
            else {
                comp.buckets = response.Buckets;
            }
        })
    }

this.getS3() is a method I wrote to create an S3 instance. This is how it looks:

private getS3() {
        var currentUser = this.accountInfoService.getCurrentUser();
        AWS.config.update({ accessKeyId: currentUser.accessKeyId, secretAccessKey: currentUser.secretAccessKey });
        var Logger = { log: function(line) { console.log(line) } };
        if (currentUser.isECS) {
            console.log(currentUser.isECS);
            var ep = new AWS.Endpoint('http://' + currentUser.endPoint);
            var s3 = new AWS.S3({ endpoint: ep, s3ForcePathStyle: true, logger: Logger, sslEnabled: false });
        }
        else {
            var s3 = new AWS.S3();
        }
        return s3;
    }

Can someone please tell me what I am doing wrong here.