(window.webpackJsonp=window.webpackJsonp||[]).push([[139],{466:function(t,s,a){"use strict";a.r(s);var n=a(3),e=Object(n.a)({},(function(){var t=this,s=t._self._c;return s("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[s("h1",{attrs:{id:"dom"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#dom"}},[t._v("#")]),t._v(" DOM")]),t._v(" "),s("h2",{attrs:{id:"一、概述"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#一、概述"}},[t._v("#")]),t._v(" 一、概述")]),t._v(" "),s("h3",{attrs:{id:"_1、dom"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1、dom"}},[t._v("#")]),t._v(" 1、DOM")]),t._v(" "),s("p",[s("strong",[t._v("DOM 是 JavaScript 操作网页的接口")]),t._v("，全称为“"),s("strong",[t._v("文档对象模型")]),t._v("”（Document Object Model）。它的"),s("strong",[t._v("作用")]),t._v("是"),s("strong",[t._v("将网页转为一个 JavaScript 对象，从而可以用脚本进行各种操作")]),t._v("（比如增删内容）。")]),t._v(" "),s("p",[t._v("浏览器会根据 DOM 模型，将结构化文档（比如 HTML 和 XML）解析成一系列的节点，再由这些节点组成一个树状结构（DOM Tree）。所有的节点和最终的树状结构，都有规范的对外接口。")]),t._v(" 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"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// #text")]),t._v("\nconsole"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("log")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("textNode"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nodeValue"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 'hello world'")]),t._v("\n\ntextNode"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nodeValue "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'123'")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 修改文本")]),t._v("\nconsole"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token 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"),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br"),s("span",{staticClass:"line-number"},[t._v("6")]),s("br"),s("span",{staticClass:"line-number"},[t._v("7")]),s("br"),s("span",{staticClass:"line-number"},[t._v("8")]),s("br"),s("span",{staticClass:"line-number"},[t._v("9")]),s("br"),s("span",{staticClass:"line-number"},[t._v("10")]),s("br"),s("span",{staticClass:"line-number"},[t._v("11")]),s("br"),s("span",{staticClass:"line-number"},[t._v("12")]),s("br"),s("span",{staticClass:"line-number"},[t._v("13")]),s("br"),s("span",{staticClass:"line-number"},[t._v("14")]),s("br"),s("span",{staticClass:"line-number"},[t._v("15")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("div")]),t._v("是元素节点，"),s("code",[t._v("nodeValue")]),t._v("属性返回"),s("code",[t._v("null")]),t._v("。"),s("code",[t._v("div.firstChild")]),t._v("是文本节点，所以可以返回文本值。")]),t._v(" "),s("h4",{attrs:{id:"_1-4-node-prototype-textcontent所有文本内容"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-4-node-prototype-textcontent所有文本内容"}},[t._v("#")]),t._v(" 1.4 Node.prototype.textContent所有文本内容")]),t._v(" "),s("p",[s("code",[t._v("textContent")]),t._v("属性"),s("strong",[t._v("返回当前节点和它的所有后代节点的文本内容")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// HTML 代码为")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v('//

This is some text

')]),t._v("\n\ndocument"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'divA'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("textContent\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// This is some text")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br")])]),s("p",[s("code",[t._v("textContent")]),t._v("属性自动忽略当前节点内部的 HTML 标签，返回所有文本内容。")]),t._v(" "),s("p",[t._v("该属性是"),s("strong",[t._v("可读写")]),t._v("的，设置该属性的值，会用一个新的文本节点，替换所有原来的子节点。它还有一个好处，就是自动对 HTML 标签转义。这很适合用于用户提供的内容。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[t._v("document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'foo'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("textContent "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'

GoodBye!

'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 写入文本")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("p",[t._v("上面代码在插入文本时，"),s("strong",[t._v("会将"),s("code",[t._v("

")]),t._v("标签解释为文本")]),t._v("，而不会当作标签处理。")]),t._v(" "),s("p",[t._v("对于文本节点（text）、注释节点（comment）和属性节点（attr），"),s("code",[t._v("textContent")]),t._v("属性的值与"),s("code",[t._v("nodeValue")]),t._v("属性相同。对于其他类型的节点，该属性会将每个子节点（不包括注释节点）的内容连接在一起返回。如果一个节点没有子节点，则返回空字符串。")]),t._v(" "),s("p",[t._v("文档节点（document）和文档类型节点（doctype）的"),s("code",[t._v("textContent")]),t._v("属性为"),s("code",[t._v("null")]),t._v("。如果要"),s("strong",[t._v("读取整个文档的内容")]),t._v("，可以使用"),s("code",[t._v("document.documentElement.textContent")]),t._v("。")]),t._v(" "),s("h4",{attrs:{id:"_1-5-node-prototype-baseuri-获取网页路径"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-5-node-prototype-baseuri-获取网页路径"}},[t._v("#")]),t._v(" 1.5 Node.prototype.baseURI 获取网页路径")]),t._v(" "),s("p",[s("code",[t._v("baseURI")]),t._v("属性"),s("strong",[t._v("返回一个字符串，表示当前网页的绝对路径")]),t._v("。浏览器根据这个属性，计算网页上的相对路径的 URL。该属性为"),s("strong",[t._v("只读")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js 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"),s("h4",{attrs:{id:"_1-7-node-prototype-nextsibling下一个同级节点"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-7-node-prototype-nextsibling下一个同级节点"}},[t._v("#")]),t._v(" 1.7 Node.prototype.nextSibling下一个同级节点")]),t._v(" "),s("p",[s("code",[t._v("Node.nextSibling")]),t._v("属性"),s("strong",[t._v("返回紧跟在当前节点后面的第一个同级节点")]),t._v("。如果当前节点后面没有同级节点，则返回"),s("code",[t._v("null")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// HTML 代码如下")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v('//

hello

world

')]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" d1 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'d1'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" d2 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token 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"),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br"),s("span",{staticClass:"line-number"},[t._v("6")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("d1.nextSibling")]),t._v("就是紧跟在"),s("code",[t._v("d1")]),t._v("后面的同级节点"),s("code",[t._v("d2")]),t._v("。")]),t._v(" "),s("p",[s("strong",[t._v("注意")]),t._v("，该属性还包括文本节点和注释节点（"),s("code",[t._v("\x3c!-- comment --\x3e")]),t._v("）。因此如果当前节点后面有空格，该属性会返回一个文本节点，内容为空格。")]),t._v(" "),s("p",[s("code",[t._v("nextSibling")]),t._v("属性可以用来遍历所有子节点。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" el 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punctuation"}},[t._v("{")]),t._v("\n console"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("log")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("el"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nodeName"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n el "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" el"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nextSibling"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br"),s("span",{staticClass:"line-number"},[t._v("6")]),s("br")])]),s("p",[t._v("上面代码遍历"),s("code",[t._v("div1")]),t._v("节点的所有子节点。")]),t._v(" "),s("h4",{attrs:{id:"_1-8-node-prototype-previoussibling上一个同级节点"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-8-node-prototype-previoussibling上一个同级节点"}},[t._v("#")]),t._v(" 1.8 Node.prototype.previousSibling上一个同级节点")]),t._v(" "),s("p",[s("code",[t._v("previousSibling")]),t._v("属性"),s("strong",[t._v("返回当前节点前面的、距离最近的一个同级节点")]),t._v("。如果当前节点前面没有同级节点，则返回"),s("code",[t._v("null")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js 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hello

world

')]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" d1 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'d1'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" d2 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'d2'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n\nd2"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("previousSibling "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("===")]),t._v(" d1 "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// true")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br"),s("span",{staticClass:"line-number"},[t._v("6")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("d2.previousSibling")]),t._v("就是"),s("code",[t._v("d2")]),t._v("前面的同级节点"),s("code",[t._v("d1")]),t._v("。")]),t._v(" "),s("p",[s("strong",[t._v("注意")]),t._v("，该属性还包括文本节点和注释节点。因此如果当前节点前面有空格，该属性会返回一个文本节点，内容为空格。")]),t._v(" "),s("h4",{attrs:{id:"_1-9-node-prototype-parentnode父节点"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-9-node-prototype-parentnode父节点"}},[t._v("#")]),t._v(" 1.9 Node.prototype.parentNode父节点")]),t._v(" "),s("p",[s("code",[t._v("parentNode")]),t._v("属性"),s("strong",[t._v("返回当前节点的父节点")]),t._v("。对于一个节点来说，它的父节点只可能是三种类型：元素节点（element）、文档节点（document）和文档片段节点（documentfragment）。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("node"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("parentNode"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n node"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("parentNode"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("removeChild")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("node"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// node的父节点，然后删除子节点node")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br")])]),s("p",[t._v("上面代码中，通过"),s("code",[t._v("node.parentNode")]),t._v("属性将"),s("code",[t._v("node")]),t._v("节点从文档里面移除。")]),t._v(" "),s("p",[t._v("文档节点（document）和文档片段节点（documentfragment）的父节点都是"),s("code",[t._v("null")]),t._v("。另外，对于那些生成后还没插入 DOM 树的节点，父节点也是"),s("code",[t._v("null")]),t._v("。")]),t._v(" "),s("h4",{attrs:{id:"_1-10-node-prototype-parentelement-父元素节点"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-10-node-prototype-parentelement-父元素节点"}},[t._v("#")]),t._v(" 1.10 Node.prototype.parentElement 父元素节点")]),t._v(" "),s("p",[s("code",[t._v("parentElement")]),t._v("属性"),s("strong",[t._v("返回当前节点的父元素节点")]),t._v("。如果当前节点没有父节点，或者父节点类型不是元素节点，则返回"),s("code",[t._v("null")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language- line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-text"}},[s("code",[t._v("if (node.parentElement) {\n node.parentElement.style.color = 'red';\n}\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br")])]),s("p",[t._v("上面代码中，父元素节点的样式设定了红色。")]),t._v(" "),s("p",[t._v("由于父节点只可能是三种类型：元素节点、文档节点（document）和文档片段节点（documentfragment）。"),s("code",[t._v("parentElement")]),t._v("属性相当于把后两种父节点都排除了。")]),t._v(" "),s("h4",{attrs:{id:"_1-11-node-prototype-firstchild-第一个子节点-node-prototype-lastchild-最后一个子节点"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-11-node-prototype-firstchild-第一个子节点-node-prototype-lastchild-最后一个子节点"}},[t._v("#")]),t._v(" 1.11 Node.prototype.firstChild 第一个子节点，Node.prototype.lastChild 最后一个子节点")]),t._v(" "),s("p",[s("code",[t._v("firstChild")]),t._v("属性"),s("strong",[t._v("返回当前节点的第一个子节点")]),t._v("，如果当前节点没有子节点，则返回"),s("code",[t._v("null")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js 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First span

')]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" p1 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'p1'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\np1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("firstChild"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nodeName "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v('// "SPAN"')]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("p")]),t._v("元素的第一个子节点是"),s("code",[t._v("span")]),t._v("元素。")]),t._v(" "),s("p",[s("strong",[t._v("注意")]),t._v("，"),s("code",[t._v("firstChild")]),t._v("返回的除了元素节点，"),s("strong",[t._v("还可能是文本节点或注释节点")]),t._v("。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// HTML 代码如下")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v('//

')]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// First span")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("//

")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" p1 "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'p1'")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\np1"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("firstChild"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("nodeName "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v('// "#text"')]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br"),s("span",{staticClass:"line-number"},[t._v("2")]),s("br"),s("span",{staticClass:"line-number"},[t._v("3")]),s("br"),s("span",{staticClass:"line-number"},[t._v("4")]),s("br"),s("span",{staticClass:"line-number"},[t._v("5")]),s("br"),s("span",{staticClass:"line-number"},[t._v("6")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("p")]),t._v("元素与"),s("code",[t._v("span")]),t._v("元素之间有空白字符，这导致"),s("code",[t._v("firstChild")]),t._v("返回的是文本节点。")]),t._v(" "),s("p",[s("code",[t._v("lastChild")]),t._v("属性"),s("strong",[t._v("返回当前节点的最后一个子节点")]),t._v("，如果当前节点没有子节点，则返回"),s("code",[t._v("null")]),t._v("。用法与"),s("code",[t._v("firstChild")]),t._v("属性相同。")]),t._v(" "),s("h4",{attrs:{id:"_1-12-node-prototype-childnodes-所有子节点-类数组对象-动态集合"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#_1-12-node-prototype-childnodes-所有子节点-类数组对象-动态集合"}},[t._v("#")]),t._v(" 1.12 Node.prototype.childNodes 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"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 包含元素节点、文本节点、注释节点")]),t._v("\n")])]),t._v(" "),s("div",{staticClass:"line-numbers-wrapper"},[s("span",{staticClass:"line-number"},[t._v("1")]),s("br")])]),s("p",[t._v("上面代码中，"),s("code",[t._v("children")]),t._v("就是"),s("code",[t._v("ul")]),t._v("元素的所有子节点。")]),t._v(" "),s("p",[t._v("使用该属性，可以遍历某个节点的所有子节点。")]),t._v(" "),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" div "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("getElementById")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token string"}},[t._v("'div1'")]),s("span",{pre:!0,attrs:{class:"token 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"),s("div",{staticClass:"language-js line-numbers-mode"},[s("pre",{pre:!0,attrs:{class:"language-js"}},[s("code",[s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" children "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" document"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("childNodes"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i "),s("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v(" children"),s("span",{pre:!0,attrs:{class:"token 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参数节点在当前节点的前面（2）")]),t._v("\n")])]),t._v(" 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punctuation"}},[t._v("(")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n console"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),s("span",{pre:!0,attrs:{class:"token function"}},[t._v("log")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("key"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 返回键名")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 0")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 1")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 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punctuation"}},[t._v("(")]),t._v("value"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" "),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 返回键值 (即节点名)")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// #text")]),t._v("\n"),s("span",{pre:!0,attrs:{class:"token comment"}},[t._v("//