Topics to be discussed: Functions, passing functions, anonymous functions, arrow functions.

What do you mean by functions?

function print(name) {
  return "Hello " + name
  console.log("this will never execute")
}

We can call (invoke) this function like this Once we have returned something it will go back to the previous call and return the value to it. Here we have a single call of Dad function only. But if you are aware of recursion, you already know, why I am talking about the previous call.

print()

Passing function to another function

function Dad(text2, son) {
  son("hello " + text2)
}

function son(text1) {
  console.log(text1)
}

Dad("saurav", son)

We created a function Dad and while calling it we passed a string and another function "son".
But if we pass son() instead of son, it will return undefined because it does not return any value. We can use + symbol to concatenate strings. Inside our function, we are calling our function son.

console.log("any text") is used to print the value in Javascript
Also, we can treat functions as variables

let a = function sum(){
            return a+b
            }
console.log(a)

It will print the exactly same thing that is written inside the ``` variable a

# Anonymous function

It is that function which doesn't have any name. It will be used more in case of arrow function. Instead of passing name of variable into calling function ,  we can create an anonymous function.
<br>
### If we don't use anonymous function

```JAVASCRIPT
function a(name){
    b("hi "+name)
}
/*
we can use any variable .. bcoz it is a prototype
but to understand it without any confusion I am passing name
*/

function b(name){
    console.log(name)
}

a("saurav")

If we use an anonymous function

function a(text,anyNameHere){
    anyNameHere("hi "+text)
}
/*
we can use any variable .. bcoz it is a prototype
but to understand it without any confusion I am passing name
*/


// using two arguments bcoz its prototype also has two arguments
//"saurav" willl be copied inside name variable
//anonymous function will be copied inside anyNameHere variable
a("saurav",function b(name){
    console.log(name)
})

Arrow Functions

Arrow functions are similar to anonymous functions. It makes our code less bulky and improves our readability.

//called or callee function
function abc(x , anyNameHere){
      anyNameHere(x)
}

// calling function
abc("saurav", (name)=>{
       console.log(name)
})

It can be used anywhere. If you don't have any arguments then you can use like this

let variableName = ()=> console.log("I have no arguments " )
// parenthesis are optional if you don't have any argument or single arguments

//calling function
variableName( )

If you have more than one argument then you can use like this

// function sum(a, b) {
//   return a + b
// }

//same thing can be done with the help of arrow functions

let sum = (a, b) => a + b
//don't add return in case of single line statement in arrow function
//bcoz arrow function automatically adds return in its first line

console.log(sum(2, 3))

Output

5

let func = (a, b) => {
  a = a + b
  return "new value of a is " + a
}
console.log(func(2, 3))

new value of a is 5

Both the normal function and the arrow function show different behaviour while using the "this" keyword. I will add this topic later.

Comment down below if I have made any mistake.