Uncaught ReferenceError: kpoejy is not defined

You’re not properly defining the JS object. The following will work

var kpoejy = {
        updateSignupEmail: function() {
            // code
        }
    };

Because now you’re making kpoejy an object (via {}) and inside assign the key updateSignupEmail a function.

What you did previously was to assign kpoejy a function, and inside that define another function.