addOne

addOne.js

/** @const */ var ONE = 1;

/**
 * A function to add 1 to a number.
 * @param  {number} n a number to be added.
 * @return {number} The number + 1.
 */
var addOne = function (n) {
    return n + ONE;
}

/** @type {number} */ var num = null;
console.log(addOne(num));