Explicit Type Conversion and typeof in JavaScript

Question

    var x = +"5";    // 5
    alert("string to number explicitly: "+typeof x); //  number

Now consider this:

When we convert a string to a number, the result is the numeric value of a string if it is simply a number; all other strings become NaN

var y = +"foo";  //NaN
alert(typeof y); // Why this results in number?

Answer 1

typeof NaN is as a "number" and it's expected behavior. Further information: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN

Answer 2

Its shortest form to convert a variable to number. +anything is trying to convert anything to number.

As "foo" is a string and not a valid number thus it returns NaN