By GokiSoft.com| 10:01 18/01/2021|
Học JS

[Share Code] Tìm hiểu Javascript biến, toán tử, hàm căn bản, function - Lập trình HTML/CSS/JS 



Kien thuc JS
	- JS Core:
		- khai bao bien, toan tu, bieu thuc logic
		- Menh de dieu kien (if, else, switch)
		- Loop: while, for, do .. while
		- Function
		- Object & Array
	- JS advanced
		- Event
		- Tuong tac len tags html (doc noi dung tag, thay doi noi dung tags, .v.v)
		- LocalStorage: Luu tru du lieu (Cookie, Session, )




<!DOCTYPE html>
<html>
<head>
	<title>Javascript tutorial</title>
	<meta charset="utf-8">
</head>
<body>
	<h1 id="title">Welcome to learn Javascript</h1>

	<button onclick="clickX()">Nhap x</button>
	<button onclick="clickY()">Nhap y</button>
	<button onclick="clickKQ()">In Ket Qua</button>

	<script type="text/javascript">
		//code js
		// var font = 0;

		// setInterval(function() {
		// 	var titleTag = document.getElementById('title')
		// 	titleTag.style.fontSize = ++font + "px"
		// 	var a = Math.random() * 255
		// 	var b = Math.random() * 255
		// 	var c = Math.random() * 255
		// 	titleTag.style.color = `rgb(${a}, ${b}, ${c})`
		// }, 100)

		// Khai bao bien
		var a = 10 //a => so nguyen
		var b = "Xin chao" //b => String, text, mang ky tu
		a = "Good morning" //a => Hieu la String, text, mang ky tu
		a = 'Xin chao' //a => String, text, mang ky tu

		// document.write(a) //Su dung test => Trong lap trinh => khong dung
		console.log(a)

		x = "TRAN VAN A"
		console.log(x)
		// Toan tu, +, -, *, /, %
		var x = 5
		var y = 6
		var z = x + y
		console.log(z)
		var t = "6"
		k = x + t
		console.log(k)
		k = x - t
		console.log(k)
		k = x * t
		console.log(k)
		k = x / t
		console.log(k)
		//Tinh tong cua x + t => 11
		k = x + t*1
		console.log(k)
		k = x + parseInt(t)
		console.log(k)
		// Mot so function can ban
		// alert('May ban da bi nhieu virus')
		// option = confirm('Ban co muon xoa thong tin tai khoan nay khong???')
		// console.log(option)
		// code = 'var t1 = 5; t2 = ++t1; console.log(t2)'
		// console.log(code)
		// eval(code)
		// x = prompt('Nhap gia tri x')
		// y = prompt('Nhap gia tri y')

		// t = parseInt(x) + parseInt(y)

		// console.log(t)
		// x = 5
		// y = ++x
		// console.log(y)
		// console.log(x)

		// t = (x==5)?"Gia tri 5":"Gia tri khac 5"
		// console.log(t)

		// var quantity = prompt('Enter quantity of product:',0);
		// if(quantity < 0 || isNaN(quantity))
		// {
		// 	alert('Please enter a positive number.');
		// }

		// var firstNumber = prompt('Enter first number:',0);
		// var secondNumber = prompt('Enter second number',0);
		// var result = 0;
		// if (secondNumber == 0)
		// {
		// 	alert('ERROR Message: Cannot divide by zero.');
		// }
		// else
		// {
		// 	result = firstNumber/secondNumber;
		// 	alert('Result: ' + result);
		// }

		var t = 5;

		switch(t) {
			case 1:
				console.log('Xin chao')
			break;
			case 5:
				console.log('Abc...')
			break;
			default:
				console.log('khac...')
			break;
		}

		function showAlert() {
			alert('Xin chao...')
		}

		// showAlert()

		function tinhtong(n) {
			var sum = 0
			for (var i = 1; i <= n; i++) {
				sum += i
			}
			console.log(sum)
		}
		tinhtong(10)
		tinhtong(4)

		function cong(x, y) {
			var sum = x + y
			console.log(sum)
		}

		cong(2, 6)

		function tru(x, y) {
			return x - y
		}

		var kq = tru(6, 2)
		console.log('Phep tru: ' + kq)

		var x, y;

		function clickX() {
			x = prompt('Nhap x')
			console.log("x: " + x)
		}

		function clickKQ() {
			kq = parseInt(x) + parseInt(y)
			console.log("kq: " + kq)
		}

		function clickY() {
			y = prompt('Nhap y')
			console.log("y: " + y)
		}
	</script>
</body>
</html>




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