When using Cognito credentials with AWS in a browser (javascript), keep getting "missing credentials" error

Question

I'm attempting to upload a file to an S3 bucket of mine from a web browser using AWS' JavaScript SDK. My code looks like this:

AWS.config.credentials = new AWS.CognitoIdentityCredentials({
    AccountId: 'dfhgdh',
    IdentityPoolId: 'fdagsd',
    RoleArn: 'fdafds'
});

var bucket = new AWS.S3({params: {Bucket: 'test-bucket'}});
var pdfUpload = document.getElementById('pdf-uploads').files[0];

var params = {Key: pdfUpload.name, ContentType: pdfUpload.type, Body: pdfUpload};
bucket.putObject(params, function (error, data) {
    if (error) {
        console.log(error);
    } else {
        console.log(data);
    }
});

However, whenever it reaches the putObject command, I keep getting an error back from AWS:

"Error: Missing credentials in config {message: "Missing credentials in config", code: "CredentialsError"..."

I'm sure I'm missing something simple and stupid here, but I can't figure out what for the life of me. (I get a different error when I try to just hardcode a bogus secret key in or something, so I'm pretty sure it has something to do with the way I'm trying to set up cognito credentials.)

Answer 1

Turns out that after debugging the JavaScript AWS SDK, the problem was that I wasn't setting the region before setting the credentials... And for some reason, I need to use the update method, as well. I think this seems like a bug with the SDK, but the following setup of AWS.config fixed my problem:

AWS.config.region = 'us-east-1';
AWS.config.update({
    credentials: new AWS.CognitoIdentityCredentials({
        AccountId: '43243243243',
        RoleArn: 'arn:aws:iam::970123460807:role/Cognito_RigUpWebUnauth_DefaultRole',
        IdentityPoolId: 'us-east-1:432432-432432432-4324323423-423243'
    })
});