type coercion in JavaScript with + operator

sum.js

function sum() {
    var a = new Number('3');
    //Converts String value '3' to numeric value 3
    var b = +'4';
    //Converts String value '4' to numeric value 4
    var c = a + b;
    //If there is any issue in conversion it must return NaN as output
    console.log(c);
    // Output is numeric value 7
}
sum();