Difference between functions expression and function declaration in javascript:

 Function expression:

Expression will return a result immediately .

ex:2+3 will return 5.so this is a expression.

similarly , assume a function expression-

<script>

    var calSub = function(x, y){

        return x - y;

    }

 

    console.log("Subtraction : " + calSub(7, 4));

 </script>

here calSub is a function expression.

Function declaration:

A function is a set of statements that performs some task or does some computations and will return the result to the user.

Ex:

function calcAddition(number1, number2) 

{ 

    return number1 + number2; 

}