<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>冒泡排序與作用域</title>
</head>
<body>
<script>
window.onload = function() {
// 冒泡排序
var array = [0, 5, 7, 3, 2, 9, 8, 5, 4];
for (let i = 0; i < array.length - 1; i++) {
for (let j = 0; j < array.length - 1 - i; j++) {
if (array[j] > array[j + 1]) {
[array[j], array[j + 1]] = [array[j + 1], array[j]];
}
}
}
console.log(array + "");
array = [0, 5, 7, 3, 2, 9, 8, 5, 4];
console.log(
array.sort((a, b) => {
return a - b;
}) + ""
);
// 作用域
function fun() {
var a = 1;
}
fun();
try {
console.log(a); // ReferenceError: a is not defined
} catch (error) {
console.error(error);
}
function fun() {
b = 1; // 提升到全局
}
fun();
console.log(b); // 1
var a1 = 1;
function fun1() {
console.log(a1); // undefined (預解析 變量提升)
var a1 = 2;
console.log(a1); // 2
}
fun1();
console.log(a1); // 1 輸出全局變量
var s = 10;
function f() {
var b = 2 * s;
var s = 20;
var c = s + 1;
console.log(b); // 2*undefined NaN
console.log(c); // 21
}
f();
};
</script>
</body>
</html>
