Function Declaration and Function Expression in JavaScript

Function Declaration

function keyword is the first word in statement then it is a function declaration.

Just as variable declaration must start with "var", function declaration must begin with "function".

Function Expression

function keyword is not the first word in statement then it is a function expression.

function expression can be Anonymous function expression or named function expression



Link 1 - Function Declaration
Link 2 - Anonymous Function Expression
Link 3 - Named Function Expression