关于javascript:实现搜索高亮

content: {  type: String,  default: ''},keyword: {  type: String,  default: ''},highlightStyle: {  type: String,  default: 'background: #ffff00'},currentStyle: {  type: String,  default: 'background: #ff9632'},regExp: {  type: Boolean,  default: false}

},
data () {

return {  lightIndex: 0,  matchCount: 0,  contentShow: '',  random: `${Math.random()}`.slice(2)}

},
computed: {

watchString () {  return [this.content, this.keyword]},watchStyle () {  return [this.lightIndex, this.highlightStyle, this.currentStyle]},flag () {  return `${PLUGIN_FLAG}${this.random}`},styleSelector () {  return `style[${this.flag}]`},

},
watch: {

watchString: {  immediate: true,  handler () {    this.replaceKeywords()  }},watchStyle: {  immediate: true,  handler () {    this.setStyle()  }},lightIndex: {  immediate: true,  handler () {    this.$emit('current-change', this.lightIndex)  }},matchCount: {  immediate: true,  handler () {    this.$emit('match-count-change', this.matchCount)  }}

},
beforeDestroy () {

this.clearStyle()

},
methods: {

getTextNodeList (dom) {  const nodeList = [...dom.childNodes]  const textNodes = []  while (nodeList.length) {    const node = nodeList.shift()    if (node.nodeType === node.TEXT_NODE) {      node.wholeText && textNodes.push(node)    } else {      nodeList.unshift(...node.childNodes)    }  }  return textNodes},getTextInfoList (textNodes) {  let length = 0  const textList = textNodes.map(node => {    let startIdx = length, endIdx = length + node.wholeText.length    length = endIdx    return {      text: node.wholeText,      startIdx,      endIdx    }  })  return textList},getMatchList (content, keyword) {  if (!this.regExp) {    const characters = [...'\\[](){}?.+*^$:|'].reduce((r, c) => (r[c] = true, r), {})    keyword = keyword.split('').map(s => characters[s] ? `\\${s}` : s).join('[\\s\\n]*')  }  const reg = new RegExp(keyword, 'gmi')  const matchList = []  let match = reg.exec(content)  while (match) {    matchList.push(match)    match = reg.exec(content)  }  return matchList},replaceMatchResult (textNodes, textList, matchList) {  // 对于每一个匹配后果，可能扩散在多个标签中，找出这些标签，截取匹配片段并用font标签替换出  for (let i = matchList.length - 1; i >= 0; i--) {    const match = matchList[i]    const matchStart = match.index, matchEnd = matchStart + match[0].length // 匹配后果在拼接字符串中的起止索引    // 遍历文本信息列表，查找匹配的文本节点    for (let textIdx = 0; textIdx < textList.length; textIdx++) {      const { text, startIdx, endIdx } = textList[textIdx] // 文本内容、文本在拼接串中开始、完结索引      if (endIdx < matchStart) continue // 匹配的文本节点还在前面      if (startIdx >= matchEnd) break // 匹配文本节点曾经解决完了      let textNode = textNodes[textIdx] // 这个节点中的局部或全部内容匹配到了关键词，将匹配局部截取进去进行替换      const nodeMatchStartIdx = Math.max(0, matchStart - startIdx) // 匹配内容在文本节点内容中的开始索引      const nodeMatchLength = Math.min(endIdx, matchEnd) - startIdx - nodeMatchStartIdx // 文本节点内容匹配关键词的长度      if (nodeMatchStartIdx > 0) textNode = textNode.splitText(nodeMatchStartIdx) // textNode取后半局部      if (nodeMatchLength < textNode.wholeText.length) textNode.splitText(nodeMatchLength)      const font = document.createElement('font')      font.setAttribute(this.flag, i + 1)      font.innerText = text.substr(nodeMatchStartIdx, nodeMatchLength)      textNode.parentNode.replaceChild(font, textNode)    }  }},replaceKeywords () {  let flag = false  if (this.regExp) {    try {      const reg = new RegExp(this.keyword)      if (reg.test('')) flag = 1    } catch (err) {      flag = 1    }  }  if (flag || !this.keyword) {    this.contentShow = this.content    return  }  const div = document.createElement('div')  div.innerHTML = this.content  const textNodes = this.getTextNodeList(div)  const textList = this.getTextInfoList(textNodes)  const content = textList.map(({ text }) => text).join('')  const matchList = this.getMatchList(content, this.keyword)  this.matchCount = matchList.length  this.lightIndex = this.matchCount ? 1 : 0  this.replaceMatchResult(textNodes, textList, matchList)  this.contentShow = div.innerHTML},scrollTo (index) {  this.$nextTick(() => {    let node = this.$el.querySelector(`font[${this.flag}='${index}']`)    if (node) {      this.lightIndex = index      node.scrollIntoView()    }  })},searchNext () {  this.$nextTick(() => {    let idx = this.lightIndex >= this.matchCount ? 1 : this.lightIndex + 1    this.scrollTo(idx)  })},searchLast () {  this.$nextTick(() => {    let idx = this.lightIndex <= 1 ? this.matchCount : this.lightIndex - 1    this.scrollTo(idx)  })},setStyle () {  let style = document.head.querySelector(this.styleSelector)  if (!style) {    style = document.createElement('style')    style.setAttribute(this.flag, 1)  }  style.innerText = `font[${this.flag}]{${this.highlightStyle}}font[${this.flag}='${this.lightIndex}']{${this.currentStyle}}`  document.head.appendChild(style)},clearStyle () {  let style = document.head.querySelector(this.styleSelector)  style && document.head.removeChild(style)}

}
}
</script>