JavaScript/lesson-12/AdvanceFunction.html at main · deep100x/JavaScript · GitHub

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<!-- in this lesson: -->
<!-- ------------------- -->
<!--

    Lesson 12 : Advance Functions

    1. Functions are values
    2. setTimeout(), setInterval()
    3. forEach()
    4. Arrow functions, .addEvenListener()
    5. filter(), map()
	6. Closure

-->

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>Document</title>
	</head>
	<body>
		<button onclick="" class="js-button">Click</button>

		<script>
			greeting() //🟨-Hoisting  Declaration before Initialization
			function greeting() {
				console.log("hello")
			}
			greeting()

			const num = 2
			//🟨-Functions are values ( we can save it in a variable )
			const function1 = function () /*-🟨Anonymous function (without name)*/ {
				console.log("hello2")
			}

			console.log(function1)
			console.log(typeof function1)
			function1()

			//🟨-Can save a value in a object ✔
			const object1 = {
				num: 2,
				fun: function () {
					//🟨-Method ( Function saved inside an object )
					console.log("hello3")
				},
			}
			object1.fun()

			//🟨-Passing a value into a function
			function display(param) {
				console.log(param)
			}
			display(2)

			function run(param) {
				param()
			}
			run(function () {
				console.log("hello4")
			})

			//🟨-setTimeout()
			//🟩-allows us to run a function in the future
			setTimeout(function () {
				console.log("timeout")
				console.log("timeout2")
			}, 3000)
			//🟨-How long to wait before running this function (milliseconds)

			//🟨-Asyncronous Code ( won't wait for a line to finish before going to the next line )
			console.log("next line")

			//🟨-setInterval
			setInterval(function () {
				console.log("interval")
			}, 3000)
			//🟩-Keep running the function every 3 seconds
			console.log("next line2")

			x = [("make dinner", "wash dishes", "watch youtube")].forEach((value, index) => {
				if (value === "wash dishes") {
					return
				}
				console.log(index)
				console.log(value)
			})

			//🟨if we want to use break; then its better to use a regular for loop.

			//🟨-Regular Functions
			const regularFunction = function (param, param2) {
				console.log("hello")
			}

			//🟨-Arrow Functions
			const arrowFunction = (param, param2) => {
				console.log("hello")
				return 5
			}
			arrowFunction()

			const oneParam = (param) => {
				console.log(param + 1)
			}
			oneParam(2)

			//🟨 Shortcut
			const oneLine = () => 2 + 3
			console.log(oneLine())

			const object2 = {
				method: () => {},
				method() {},
			}

			//🟨-addEventListener
			const buttonElement = document.querySelector(".js-button")

			const eventListener = () => {
				console.log("click")
			}
			buttonElement.addEventListener("click", eventListener)
			buttonElement.addEventListener("click", () => {
				console.log("click2")
			})

			//🟨-removeEventListener
			buttonElement.removeEventListener("click", eventListener)

			//🟨 .filter()  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
			//🟩 [1, -3, 5]  =>  [1, 5]    Negative numbers removed

			console.log(
				[1, -3, 5].filter((value, index) => {
					/*
					if (value >= 0) {
						return true
					} else {
						return false
					}
					*/
					return value >= 0
				})
			)
			//🟨 .map()  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
			//🟩 .map() = transform an array into another array

			console.log(
				[1, 1, 3].map((value, index) => {
					return value * 2
				})
			)

			//🟨 Shortcuts

			console.log([1, 1, 3].map((value) => value * 2))

			//🟨 Closure
			//🟩 if a function has access to a value
			//🟩 it will always have access to that value
			//🟩 value gets packaged together (enclosed) with function
		</script>
	</body>
</html>