Understanding Undefined Value returned from a Function

What is the let in JavaScript? let allows you to declare variables that are limited to the scope of a block statement, or expression on which it is used, unlike the var keyword, which declares a variable globally, or locally to an entire function regardless of block scope.

What is a var in JavaScript? var is the keyword that tells JavaScript you're declaring a variable. x is the name of that variable. = is the operator that tells JavaScript a value is coming up next.

What are functions for JavaScript? A function in JavaScript is similar to a procedure—a set of statements that performs a task or calculates a value, but for a procedure to qualify as a function, it should take some input and return an output where there is some obvious relationship between the input and the output.

What is a return in JavaScript? The return statement is used to return a particular value from the function to the function caller. The function will stop executing when the return statement is called. The return statement should be the last statement in a function because the code after the return statement will be unreachable.

Why do we get undefined in JavaScript? A variable that has not been assigned a value is of type undefined . A method or statement also returns undefined if the variable that is being evaluated does not have an assigned value. A function returns undefined if a value was not returned.

The addition assignment (+=) operator performs addition (which is either numeric addition or string concatenation) on the two operands and assigns the result to the left operand.

The increment (++) operator increments (adds one to) its operand and returns the value before or after the increment, depending on where the operator is placed.