js中一些常用的基本方法

alert("Hello, World!");

console.log("This is a log message.");

let intVal = parseInt("123"); // 123
let floatVal = parseFloat("123.45"); // 123.45

console.log(isNaN("Hello")); // true
console.log(isNaN(123)); // false

console.log(Math.sqrt(16)); // 4
console.log(Math.random()); // 随机数

let str = "Hello, World!";
console.log(str.toUpperCase()); // HELLO, WORLD!
console.log(str.includes("World")); // true

let arr = [1, 2, 3, 4, 5];
console.log(arr.map(x => x * 2)); // [2, 4, 6, 8, 10]
console.log(arr.filter(x => x > 2)); // [3, 4, 5]

// 2秒后执行一次
setTimeout(() => {
    console.log("This runs after 2 seconds.");
}, 2000);

// 每秒执行一次
let intervalId = setInterval(() => {
    console.log("This runs every second.");
}, 1000);

document.getElementById("myButton").addEventListener("click", function() {
    alert("Button was clicked!");
});

function fetchData() {
    return new Promise((resolve, reject) => {
        setTimeout(() => resolve("Data fetched!"), 1000);
    });
}

async function getData() {
    try {
        let data = await fetchData();
        console.log(data);
    } catch (error) {
        console.error(error);
    }
}