can i write function under function in js code example

Example: how to write a function javascript

// 3 ways you see it
function name(argument){ 
 return argument + 2
  //return something here
}
name(4) // equals 6

let name = function(arg){ return arg + 2}
name(4) //this equals 6, here we are calling our name function

//es6 style 

let name = (arg) => {return arg+ 2}
name(4) //equals 6