DOM——节点操作

节点操作

 var body = document.body;
 var div = document.createElement('div');
 body.appendChild(div);
 ​
 var firstEle = body.children[0];
 body.insertBefore(div, firstEle);
 ​
 body.removeChild(firstEle);
 ​
 var text = document.createElement('p');
 body.replaceChild(text, div);

案例：

选择水果

节点属性

• nodeType 节点的类型

  • 1 元素节点

  • 2 属性节点

  • 3 文本节点

• nodeName 节点的名称(标签名称)

• nodeValue 节点值

  • 元素节点的nodeValue始终是null

模拟文档树结构

function Node(option) {
  this.id = option.id || '';
  this.nodeName = option.nodeName || '';
  this.nodeValue = option.nodeValue || '';
  this.nodeType = 1;
  this.children = option.children || [];
}

var doc = new Node({
  nodeName: 'html'
});
var head = new Node({
  nodeName: 'head'
});
var body = new Node({
  nodeName: 'body'
})
doc.children.push(head);
doc.children.push(body);

var div = new Node({
  nodeName: 'div',
  nodeValue: 'haha',
});

var p = new Node({
  nodeName: 'p',
  nodeValue: '段落'
})
body.children.push(div);
body.children.push(p);

function getChildren(ele) {
  for(var i = 0; i < ele.children.length; i++) {
    var child = ele.children[i];
    console.log(child.nodeName);
    getChildren(child);
  }
}
getChildren(doc);

节点层级

var box = document.getElementById('box');
console.log(box.parentNode);
console.log(box.childNodes);
console.log(box.children);
console.log(box.nextSibling);
console.log(box.previousSibling);
console.log(box.firstChild);
console.log(box.lastChild);

• 注意

  childNodes和children的区别，childNodes获取的是子节点，children获取的是子元素

  nextSibling和previousSibling获取的是节点，获取元素对应的属性是nextElementSibling和previousElementSibling获取的是元素

  nextElementSibling和previousElementSibling有兼容性问题，IE9以后才支持

• 总结

节点操作，方法
	appendChild()
	insertBefore()
	removeChild()
	replaceChild()
节点层次，属性
	parentNode
	childNodes
	children
	nextSibling/previousSibling
	firstChild/lastChild