JavaScript - Function Expressions

Expanding on the anonymous function concept, we know that function do not need names. You can also take function, not give it a name, and "express" it with a lambda expression. Take this code snippet for example - this is using a function with a name called DoMath:

let a = 100;
let b = 100;
function DoMath(a,b)
{
    return a+b;
}
$("#Demo1").html(DoMath(a,b));

Here's the same thing and assigning the function to a variable called do math. This is how we invoke the function. The function itself has no name.

$(function ()
{
    let c = 101;
    let d = 101;
    let DoMath2 = function(c,d) {return c+d;};
    $("#Demo2").html(DoMath2(c,d));
});

Now we can use an function expression. Notice how I said "sum is an arrow, that takes two args and it's return is e + f "? This a function expression - aka an arrow function. The expression is assigned to a variable called sum.

$(function ()
{
    let e = 102;
    let f = 102;
    let sum = (e,f) => { return e + f; };
    $("#Demo3").html(sum(e,f));
});

We can even go one step further and remove return and the curly braces.

$(function ()
{
    let g = 103;
    let h = 103;
    let sum = (g,h) => g + h; 
    $("#Demo4").html(sum(g,h));
});