文章说明

本文主要为了书写Latex的书写风格，以及了解自己实现一个markdown类型的编辑器的过程；目前实现了当前的效果；书写文章进行记录，方便后续查阅

目前还未添加好markdown的代码高亮效果，等待后续自己实现一个高亮组件，然后添加到该demo中

文本相对复杂的几个小点为：
1、marked库的使用
2、katex库的使用
3、textarea元素的光标处插入内容的实现（本效果参考了文章：利用selection对象在textarea光标处插入指定文本）
4、滚动同步效果（目前实现的效果感觉不是很好，会有一些抖动的效果，感觉有点头晕，没有CSDN自带的编辑功能的这个同步效果的实现精细，不过我目前也没整明白它这里的实现原理是什么样的，如果有好的想法的同学欢迎提出在评论区中，如对demo有帮助，冰冰一号会进行采纳，同时添加到项目贡献者中）
Latex相关公式的查找（参考文章为：[markdown语法]公式篇–整理总结了常用的公式语法全）

实际关于markdown相关组件的使用，可以直接使用封装好的库，如v-md-editor，这种封装好的库使用相对简单，而且功能更加完善，参考链接：v-md-editor

主要代码

文件结构

markdown组件

<template>
  <div class="container">
    <textarea class="left" v-model="data.text" @scroll="scrollLeftSync"></textarea>
    <div class="right" v-html="renderedMarkdown" @scroll="scrollRightSync"></div>
  </div>
</template>

<script setup>
import {marked} from 'marked';
import {computed, onMounted, reactive} from "vue";

const data = reactive({
  text: "",
});

const renderedMarkdown = computed(() => {
  return marked.parse(data.text);
});

let left;
let right;

onMounted(() => {
  left = document.getElementsByClassName("left")[0];
  right = document.getElementsByClassName("right")[0];
  left.focus();
});

let leftScroll = true;
let rightScroll = true;

function scrollLeftSync() {
  if (!leftScroll) {
    return;
  }
  const percent = (left.scrollTop / (left.scrollHeight - left.clientHeight)).toFixed(2);
  rightScroll = false;
  right.scrollTo({
    top: (right.scrollHeight - right.clientHeight) * percent,
  });
  rightScroll = true;
}

function scrollRightSync() {
  if (!rightScroll) {
    return;
  }
  const percent = (right.scrollTop / (right.scrollHeight - right.clientHeight)).toFixed(2);
  leftScroll = false;
  left.scrollTo({
    top: (left.scrollHeight - left.clientHeight) * percent,
  });
  leftScroll = true;
}
</script>

<style lang="scss" scoped>
.container {
  width: 100%;
  height: 100%;

  .left {
    width: 50%;
    height: 100%;
    resize: none;
    border: none;
    outline: none;
    background: transparent;
    font-size: 1.4rem;
    padding: 1rem;
    display: block;
    overflow: auto;
    float: left;

    &::-webkit-scrollbar {
      width: 0.5rem;
      background-color: transparent;
      border-radius: 0.5rem;
      cursor: pointer;
    }

    &::-webkit-scrollbar-thumb {
      background-color: #bbbbbb;
      border-radius: 0.5rem;
      cursor: pointer;
    }
  }

  .right {
    width: 50%;
    height: 100%;
    background-color: #ffffff;
    font-size: 1.4rem;
    padding: 1rem;
    overflow: auto;
    float: left;

    &::-webkit-scrollbar {
      width: 0.5rem;
      height: 0.5rem;
      background-color: transparent;
      border-radius: 0.5rem;
    }

    &::-webkit-scrollbar-thumb {
      background-color: #bbbbbb;
      border-radius: 0.5rem;
    }
  }
}
</style>

Latex组件

<template>
  <div class="container">
    <div class="tool">
      <ul>
        <li @click="appendLine">换行</li>
        <li @click="superscript">上标</li>
        <li @click="subscript">下标</li>
        <li @click="vector">向量</li>
        <li @click="average">平均值</li>
        <li @click="fraction">分式</li>
        <li @click="dots">省略号</li>
        <li @click="sqrt">根式</li>
        <li @click="mul">乘</li>
        <li @click="div">除</li>
        <li @click="ge">大于等于</li>
        <li @click="le">小于等于</li>
        <li @click="ne">不等于</li>
        <li @click="dx">导数</li>
        <li @click="infinity">无穷</li>
        <li @click="leftarrow">左箭头</li>
        <li @click="rightarrow">右箭头</li>
        <li @click="In">属于</li>
        <li @click="notIn">不属于</li>
        <li @click="overbrace">上大括号</li>
        <li @click="underbrace">下大括号</li>
        <li @click="sin">sin</li>
        <li @click="cos">cos</li>
        <li @click="tan">tan</li>
        <li @click="log">log</li>
        <li @click="lg">lg</li>
        <li @click="ln">ln</li>
        <li @click="equationSet">方程组</li>
        <li @click="calculationProcess">计算过程</li>
      </ul>
    </div>
    <div class="content">
      <textarea class="left" v-model="data.text" @scroll="scrollLeftSync"></textarea>
      <div class="right" v-html="data.parseText" @scroll="scrollRightSync"></div>
    </div>
  </div>
</template>

<script setup>
import {onMounted, reactive, watch} from "vue";
import katex from 'katex'

const data = reactive({
  text: "",
  parseText: "",
});

const renderOption = {
  delimiters: [
    {left: '$$', right: '$$', display: true},
    {left: '$', right: '$', display: false},
    {left: '\\(', right: '\\)', display: false},
    {left: '\\[', right: '\\]', display: true}
  ],
  throwOnError: false
}

watch(() => data.text, () => {
  data.parseText = katex.renderToString(data.text, renderOption);
});

let left;
let right;

onMounted(() => {
  left = document.getElementsByClassName("left")[0];
  right = document.getElementsByClassName("right")[0];
  left.focus();
});

let leftScroll = true;
let rightScroll = true;

function scrollLeftSync() {
  if (!leftScroll) {
    return;
  }
  const percent = (left.scrollTop / (left.scrollHeight - left.clientHeight)).toFixed(2);
  rightScroll = false;
  right.scrollTo({
    top: (right.scrollHeight - right.clientHeight) * percent,
  });
  rightScroll = true;
}

function scrollRightSync() {
  if (!rightScroll) {
    return;
  }
  const percent = (right.scrollTop / (right.scrollHeight - right.clientHeight)).toFixed(2);
  leftScroll = false;
  left.scrollTo({
    top: (left.scrollHeight - left.clientHeight) * percent,
  });
  leftScroll = true;
}

function insertAtCursor(f, value, callback) {
  let field = f
  let newValue
  if (field.selectionStart || field.selectionStart === 0) {
    const startPos = field.selectionStart
    const endPos = field.selectionEnd
    const restoreTop = field.scrollTop
    newValue = field.value.substring(0, startPos) + value + field.value.substring(endPos, field.value.length)
    if (restoreTop > 0) {
      field.scrollTop = restoreTop
    }
    field.focus()
    setTimeout(() => {
      field.selectionStart = startPos + value.length
      field.selectionEnd = startPos + value.length
    }, 0)
  } else {
    newValue = field.value + value
    field.focus()
  }
  callback(newValue)
}

function addContent(text) {
  insertAtCursor(left, text, (newValue) => {
    data.text = newValue;
  });
}

function appendLine() {
  addContent("\n\\\\\\\n");
}

function superscript() {
  addContent(" x^y ");
}

function subscript() {
  addContent(" x_y ");
}

function vector() {
  addContent(" \\vec{a} ");
}

function average() {
  addContent(" \\overline{a} ");
}

function fraction() {
  addContent(" \\frac{1}{2} ");
}

function dots() {
  addContent(" \\cdots ");
}

function sqrt() {
  addContent(" \\sqrt[2]{x+y} ");
}

function mul() {
  addContent(" \\times ");
}

function div() {
  addContent(" \\div ");
}

function ge() {
  addContent(" \\ge ");
}

function le() {
  addContent(" \\le ");
}

function ne() {
  addContent(" \\ne ");
}

function dx() {
  addContent(" x{\\prime} ");
}

function infinity() {
  addContent(" \\infty ");
}

function leftarrow() {
  addContent(" \\leftarrow ");
}

function rightarrow() {
  addContent(" \\rightarrow ");
}

function In() {
  addContent(" \\in ");
}

function notIn() {
  addContent(" \\notin ");
}

function overbrace() {
  addContent(" \\overbrace{1+2+\\cdots+100} ");
}

function underbrace() {
  addContent(" \\underbrace{1+2+\\cdots+100} ");
}

function sin() {
  addContent(" \\sin 30^\\circ ");
}

function cos() {
  addContent(" \\cos 30^\\circ ");
}

function tan() {
  addContent(" \\tan 30^\\circ ");
}

function log() {
  addContent(" \\log_2 8 ");
}

function lg() {
  addContent(" \\lg 10 ");
}

function ln() {
  addContent(" \\ln 2 ");
}

function equationSet() {
  addContent("\nf(n)= \\begin{cases}\n" +
      "n/2, & \\text {if $n$ is even} \\\\\n" +
      "3n+1, & \\text{if $n$ is odd}\n" +
      "\\end{cases}\n");
}

function calculationProcess() {
  addContent("\n\\begin{aligned}\n" +
      "    f(x)\n" +
      "    &=x^3+3x^2+3x+1\\\\\n" +
      "    &=(x+1)^3\\\\\n" +
      "\\end{aligned}\n");
}
</script>

<style lang="scss" scoped>
.container {
  width: 100%;
  height: 100%;

  .tool {
    width: 100%;
    height: 6rem;
    border-bottom: 0.1rem solid #e0e1e2;
    background-color: #ffffff;

    ul {
      list-style: none;
      height: 3rem;
      line-height: 3rem;
      user-select: none;

      li {
        float: left;
        padding: 0 0.5rem;
        height: 3rem;
        text-align: center;
        color: #409eff;

        &:hover {
          cursor: pointer;
          color: #79bbff;
        }
      }
    }
  }

  .content {
    width: 100%;
    height: calc(100% - 6rem);

    .left {
      width: 50%;
      height: 100%;
      resize: none;
      border: none;
      outline: none;
      background: transparent;
      font-size: 1.4rem;
      padding: 1rem;
      display: block;
      float: left;

      &::-webkit-scrollbar {
        width: 0.5rem;
        background-color: transparent;
        border-radius: 0.5rem;
      }

      &::-webkit-scrollbar-thumb {
        background-color: #bbbbbb;
        border-radius: 0.5rem;
      }
    }

    .right {
      width: 50%;
      height: 100%;
      background-color: #ffffff;
      font-size: 1.4rem;
      padding: 1rem;
      overflow: auto;
      float: left;

      &::-webkit-scrollbar {
        width: 0.5rem;
        height: 0.5rem;
        background-color: transparent;
        border-radius: 0.5rem;
      }

      &::-webkit-scrollbar-thumb {
        background-color: #bbbbbb;
        border-radius: 0.5rem;
      }
    }
  }
}
</style>

效果展示

markdown编辑展示

Latex编辑展示

源码下载

冰冰markdown小工具