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JavaScript

//https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/create
var emailData = {}; //Please use Object.create instead of new {}; if that not possible you simple should use {} 
emailData.Id;
emailData.EmailAddress;

// you can also 
var emailDataArr = [
	{
		Id: 1,
    	EmailAdress : "nadf@asdfa"
	},
    {
		Id: 2,
    	EmailAdress : "adfasd@asdfa"
	},
    {
		Id: 3,
    	EmailAdress : null
	}
]; //please avoid new in all you javascript code if possible

var filter = emailDataArr.filter(function(email) {
return typeof email.EmailAdress === "string";
}); 

console.log(filter);
//you will get only emails that are strings
//[object, object];

//or you can go over each of them and compare them

emailDataArr.forEach(function(email) {
	if(typeof email.EmailAdress === "string") {
        //do your thing
    	console.log("is a string");
    }
});