- [📔 Day 7](#%f0%9f%93%94-day-7)
- [📔 Day 7](#-day-7)
- [Functions](#functions)
- [Function Declaration](#function-declaration)
- [Function without a parameter and return](#function-without-a-parameter-and-return)
@ -34,7 +34,7 @@
- [Arrow Function](#arrow-function)
- [Function with default parameters](#function-with-default-parameters)
- [Function declaration versus Arrow function](#function-declaration-versus-arrow-function)
- [💻 Exercises](#%f0%9f%92%bb-exercises)
- [💻 Exercises](#-exercises)
- [Exercises: Level 1](#exercises-level-1)
- [Exercises: Level 2](#exercises-level-2)
- [Exercises: Level 3](#exercises-level-3)
@ -79,12 +79,13 @@ Function can be declared without a parameter.
**Example:**
```js
// function without parameter, a function which square a number
// function without parameter, a function which make a number square
function square() {
let num = 2
let sq = num * num
console.log(sq)
}
square() // 4
// function without parameter
@ -95,18 +96,20 @@ function addTwoNumbers() {
console.log(sum)
}
addTwoNumbers() // function has to be called to be executed by it name
addTwoNumbers() // a function has to be called by its name to be executed
```
```js
function generateFullName (){
function printFullName (){
let firstName = 'Asabeneh'
let lastName = 'Yetayeh'
let space = ' '
let fullName = firstName + space + lastName
console.log(fullName)
}
generateFullName() // calling a function
printFullName() // calling a function
```
### Function returning value
@ -114,14 +117,14 @@ addTwoNumbers() // function has to be called to be executed by it name
Function can also return values, if a function does not return values the value of the function is undefined. Let us write the above functions with return. From now on, we return value to a function instead of printing it.
```js
function generateFullName (){
function printFullName (){
let firstName = 'Asabeneh'
let lastName = 'Yetayeh'
let space = ' '
let fullName = firstName + space + lastName
return fullName
}
console.log(generateFullName())
console.log(printFullName())
```
```js
@ -170,19 +173,20 @@ function functionName(parm1, parm2) {
//code goes her
}
functionName(parm1, parm2) // during calling or invoking two arguments needed
// Function without parameter doesn't take input, so lets make a parameter with parameter
// Function without parameter doesn't take input, so lets make a function with parameters
function sumTwoNumbers(numOne, numTwo) {
let sum = numOne + numTwo
console.log(sum)
}
sumTwoNumbers(10, 20) // calling functions
// If a function doesn't return it doesn't store data, so it should return
function sumTwoNumbersAndReturn(numOne, numTwo) {
function sumTwoNumbers(numOne, numTwo) {
let sum = numOne + numTwo
return sum
}
console.log(sumTwoNumbersAndReturn(10, 20))
console.log(sumTwoNumbers(10, 20))
function printFullName(firstName, lastName) {
return `${firstName} ${lastName}`
}
@ -222,7 +226,7 @@ console.log(areaOfCircle(10))
### Function with unlimited number of parameters
Sometimes we do not know how many arguments the user going to pass. Therefore, we should know how to write a function which can take unlimited number of arguments. The way we do it has a significant difference between a function declaration(regular function) and arrow function.Let us see examples both in function declaration and arrow function.
Sometimes we do not know how many arguments the user going to pass. Therefore, we should know how to write a function which can take unlimited number of arguments. The way we do it has a significant difference between a function declaration(regular function) and arrow function.Let us see examples both in function declaration and arrow function.
#### Unlimited number of parameters in regular function
Expression functions are anonymous functions. After we create a function without a name and with assign it to a variable. To return a value from the function we should call the variable. Look at the example below.
Expression functions are anonymous functions. After we create a function without a name and we assign it to a variable. To return a value from the function we should call the variable. Look at the example below.
```js
//Declaration function
function square(n) {
return n * n
}
console.log(square(2)) // -> 4
// Function expression
const square = function(n) {
@ -342,7 +340,7 @@ console.log(squaredNum)
Arrow function is an alternative to write a function, however function declaration and arrow function have some minor differences.
Arrow function uses arrow instead of the keyword function to declare a function. Let us see both function declaration and arrow function.
Arrow function uses arrow instead of the keyword *function* to declare a function. Let us see both function declaration and arrow function.
```js
// This is how we write normal or declaration function
@ -357,9 +355,10 @@ const square = n => {
return n * n
}
console.log(square(2)) // -> 4
// if we have only one line, it can be written as follows, explicit return
const square = n => n * n // -> 4
console.log(square(2)) // -> 4
// if we have only one line in the code block, it can be written as follows, explicit return
const square = n => n * n // -> 4
```
```js
@ -503,6 +502,8 @@ console.log('Weight of an object in Newton: ', weightOfObject(100, 1.62)) // gra
### Function declaration versus Arrow function
It ill be covered in other time
🌕 You are a rising star, now you knew function . Now, you are super charged with the power of functions. You have just completed day 7 challenges and you are 7 steps a head in to your way to greatness. Now do some exercises for your brain and for your muscle.
Asabeneh
4 years ago