JavaScript DOM与定时器基础操作指南

var elements = document.getElementById(id的名称);

var elements = document.getElementById("test");

var elements = document.getElementsByClassName(class的名称);

var elements = document.getElementsByClassName("test");

var elements = document.getElementsByTagName(标签名);

var elements = document.getElementsByClassName("p");

var element = document.querySelector(css选择的格式);

var elements = document.querySelector("a[target]");

var element = document.querySelectorAll(css选择的格式);

var elements = document.querySelectorAll("#title");

element.textContent = 文本内容;

element.textContent = "hello";

element.innerHTML = 替换的html代码;

element.textContent = "<h1>hello</h1>";

//获取父元素：
var parent = element.parentNode;
//获取子元素：
var child = element.children;
//获取同级上一个元素：
var previous = element.previousElementSibling;
//获取同级下一个元素：
var next = element.nextElementSibling;

//修改id名
//修改类名
element.className = "new-class";
//修改id名
element.id = "new-id";

//修改宽高背景颜色
element.style.backgroundColor = "red";
element.style.width = "200px";
element.style.height = "100px";
//......

例如:
···javascript
element.onclick = function() {
  //你要执行的事件
  console.log("Clicked!");
};

例如：
···javascript
element.addEventListener("click",function(){
  //你要执行的事件
  console.log("Clicked!");
});

setTimeout(回调函数,延时时间(ms));

setTimeout(function() {
    console.log("Timeout!");
}, 1000);

setInterval(回调函数,延时时间(ms));

var timerid = setInterval(function() {
    console.log("Timeout!");
}, 1000);

clearInterval(定时器id);
···
```javascript
clearInterval(timerid);
···