网页js代码大全

document.getElementById("demo").innerHTML = "Hello JavaScript!";

document.getElementById("myButton").addEventListener("click", function() {
    alert("按钮被点击了！");
});

fetch('https://api.example.com/data')
    .then(response => response.json())
    .then(data => console.log(data))
    .catch(error => console.error('Error:', error));

function validateForm() {
    var x = document.forms["myForm"]["fname"].value;
    if (x == "") {
        alert("姓名必须填写");
        return false;
    }
}

var newElement = document.createElement("p");
var textNode = document.createTextNode("这是一个新的段落。");
newElement.appendChild(textNode);
document.body.appendChild(newElement);

setTimeout(function() {
    alert("3秒后显示这条消息！");
}, 3000);

var numbers = [1, 2, 3, 4];
var doubled = numbers.map(function(num) {
    return num * 2;
});
console.log(doubled); // 输出: [2, 4, 6, 8]

const name = 'World';
const greeting = `Hello, ${name}!`;
console.log(greeting); // 输出: Hello, World!