前端开发常用工具函数与样式技巧合集

在入口文件引入即可生效：

import './scroll.scss'

2. 语音播报功能

利用 Web Speech API 实现文字转语音，无需额外依赖。

<template>
  <button @click="playVoice">播放语音</button>
</template>
<script>
const synth = window.speechSynthesis;
const msg = new SpeechSynthesisUtterance();

export default {
  methods: {
    playVoice() {
      this.handleSpeak('小朋友，你是否有很多问号');
    },
    handleSpeak(text) {
      msg.text = text;
      msg.lang = 'zh-CN';
      msg.volume = 1;
      msg.rate = 1;
      msg.pitch = 1;
      synth.speak(msg);
    },
    handleStop(e) {
      msg.text = e;
      msg.lang = 'zh-CN';
      synth.cancel(msg);
    }
  }
};
</script>

3. 手写签名组件

基于 Canvas 实现，支持清空和导出图片。

<template>
  <div style="width: 300px; height: 200px; border: 1px solid red">
    <canvas ref="canvas" class="jSignature" tabindex="0" @mousedown="onMouseDown"/>
    <footer slot="footer" class="dialog-footer">
      <el-button type="danger" @click.native.prevent="clearPanel">清空签名</el-button>
      <el-button type="primary" @click="confirm">确认签名</el-button>
      <el-button @click.native.prevent="clearPanel">取消</el-button>
    </footer>
    <img class="imgCanvas" :src="imgUrl" />
  </div>
</template>
<script>
import { defineComponent, ref, nextTick } from 'vue';

export default defineComponent({
  name: 'environAmbitus',
  setup() {
    const canvas = ref(null);
    const imgUrl = ref();

    function onMouseDown(e) {
      const el = e.target || e.srcElement;
      const ctx = el.getContext('2d');
      ctx.beginPath();
      ctx.moveTo(e.offsetX, e.offsetY);
      ctx.lineTo(e.offsetX, e.offsetY);
      ctx.stroke();

      el.onmousemove = function(e) {
        if (e.which === 0) return;
        ctx.lineTo(e.offsetX, e.offsetY);
        ctx.stroke();
      };
      el.onmouseup = function() {
        el.onmousemove = null;
        el.onmouseup = null;
      };
      el.focus();
    }

    function clearPanel() {
      nextTick(() => {
        const ctx = canvas.value.getContext('2d');
        ctx.clearRect(0, 0, canvas.value.width, canvas.value.height);
      });
    }

    function confirm() {
      nextTick(() => {
        try {
          imgUrl.value = canvas.value.toDataURL();
        } catch (e) {
          console.warn(e);
        }
      });
    }

    return { onMouseDown, confirm, clearPanel, canvas, imgUrl };
  }
});
</script>

4. 拖动改变元素宽度

实现类似表格列宽拖拽的效果，核心在于计算偏移量并限制边界。

<template>
  <div>
    <ul class="box" ref="box">
      <li class="left">西瓜</li>
      <li class="resize"></li>
      <li class="mid">备注</li>
      <li class="resize2"></li>
      <li class="right">test</li>
    </ul>
  </div>
</template>
<script>
export default {
  mounted() {
    this.dragControllerDiv();
  },
  methods: {
    dragControllerDiv() {
      const resize = document.getElementsByClassName('resize');
      const resize2 = document.getElementsByClassName('resize2');
      const left = document.getElementsByClassName('left');
      const right = document.getElementsByClassName('right');
      const mid = document.getElementsByClassName('mid');
      const box = document.getElementsByClassName('box');

      for (let i = 0; i < resize.length; i++) {
        resize[i].onmousedown = function(e) {
          const startX = e.clientX;
          resize[i].left = resize[i].offsetLeft;
          document.onmousemove = function(e) {
            const endX = e.clientX;
            const rightW = right[i].offsetWidth;
            let moveLen = resize[i].left + (endX - startX);
            const maxT = box[i].clientWidth - resize[i].offsetWidth;
            
            if (moveLen < 150) moveLen = 150;
            if (moveLen > maxT - rightW - 150) moveLen = maxT - rightW - 150;
            
            resize[i].style.left = moveLen;
            for (let j = 0; j < left.length; j++) {
              left[j].style.width = moveLen + 'px';
              mid[j].style.width = (box[i].clientWidth - moveLen - rightW - 10) + 'px';
            }
          };
          document.onmouseup = function(evt) {
            document.onmousemove = null;
            document.onmouseup = null;
            resize[i].releaseCapture && resize[i].releaseCapture();
          };
          resize[i].setCapture && resize[i].setCapture();
          return false;
        };
      }
      // resize2 逻辑类似，此处省略部分重复代码以保持简洁
    }
  }
};
</script>
<style scoped>
.box { width: 800px; height: 32px; overflow: hidden; }
.resize, .resize2 { width: 5px; cursor: w-resize; float: left; }
.left { width: calc(30% - 10px); background: skyblue; float: left; }
.mid { width: 35%; background: #f00; float: left; }
.right { width: 35%; background: tomato; float: left; }
</style>

5. 长时间未操作自动退出

结合 localStorage 记录最后操作时间，定时检测超时。

utils/storage.js

export default {
  setItem(key, value) {
    window.localStorage.setItem(key, JSON.stringify(value));
  },
  getItem(key, defaultValue) {
    let value = window.localStorage.getItem(key);
    try { value = JSON.parse(value); } catch {} 
    return value || defaultValue;
  },
  removeItem(key) { window.localStorage.removeItem(key); },
  clear() { window.localStorage.clear(); }
};

utils/astrict.js

import storage from '@/utils/storage';
import router from '@/router';
import { MessageBox } from 'element-ui';

let lastTime = new Date().getTime();
const timeOut = 1 * 60 * 60 * 1000; // 30 分钟
let showDialog = false;

window.onload = function() {
  window.document.onmousedown = function() {
    storage.setItem('lastTime', new Date().getTime());
  };
};

function checkTimeout() {
  const currentTime = new Date().getTime();
  lastTime = storage.getItem('lastTime');
  if (currentTime - lastTime > timeOut) {
    if (router.currentRoute.name === 'Start') return;
    if (!showDialog) {
      showDialog = true;
      MessageBox.alert('登录超时', '提示', {
        type: 'warning',
        showClose: false,
        duration: 5000,
        callback: () => {
          showDialog = false;
          storage.clear();
          router.push({ name: 'Start' });
        }
      });
    }
  }
}

export default function() {
  window.setInterval(checkTimeout, 30000);
}

6. iframe 自适应高度

监听窗口变化动态调整 iframe 高度，避免滚动条冲突。

<iframe src="http://www.example.com" id="myiframe" scrolling="no" frameborder="0"></iframe>
<script>
function changeFrameHeight(){
  var ifm = document.getElementById("myiframe");
  ifm.height = document.documentElement.clientHeight;
}
window.onresize = function(){ changeFrameHeight(); }
</script>

7. 浏览器环境检测

判断用户使用的浏览器类型，用于兼容性处理。

let Sys = {};
let ua = navigator.userAgent.toLowerCase();
let s;
(s = ua.match(/msie ([\d.]+)/)) ? Sys.ie = s[1] :
(s = ua.match(/firefox\/([\d.]+)/)) ? Sys.firefox = s[1] :
(s = ua.match(/chrome\/([\d.]+)/)) ? Sys.chrome = s[1] :
(s = ua.match(/opera.([\d.]+)/)) ? Sys.opera = s[1] :
(s = ua.match(/version\/([\d.]+).*safari/)) ? Sys.safari = s[1] : 0;

if (Sys.ie) alert('IE: ' + Sys.ie);
if (Sys.firefox) alert('Firefox: ' + Sys.firefox);
if (Sys.chrome) alert('Chrome: ' + Sys.chrome);

8. 文字展开与收起

根据内容高度动态控制显示区域，提升页面整洁度。

<template>
  <div class="content">
    <div v-for="(al, index) in als" :key="index">
      <div class="text more">占位</div>
      <div class="text">
        <div :class="{'retract': al.status}" :style="{'max-height': al.status ? textHeight : ''}">
          {{ al.byrw }}
        </div>
        <div class="btn">
          <p v-if="al.status" @click="al.status = false">展开</p>
          <p v-if="!al.status" @click="al.status = true">收起</p>
        </div>
      </div>
    </div>
  </div>
</template>
<script>
export default {
  data() {
    return { als: [], textHeight: null };
  },
  mounted() {
    this.$nextTick(() => this.calculateText());
  },
  methods: {
    calculateText() {
      const oneHeight = this.$refs.more.scrollHeight;
      const twoHeight = oneHeight * 2 || 40;
      this.textHeight = `${twoHeight}px`;
      const txtDom = this.$refs.textContainer;
      for (let i = 0; i < txtDom.length; i++) {
        const curHeight = txtDom[i].offsetHeight;
        if (curHeight > twoHeight) {
          this.$set(this.als, i, Object.assign({}, this.als[i], { status: true }));
        } else {
          this.$set(this.als, i, Object.assign({}, this.als[i], { status: null }));
        }
      }
    }
  }
};
</script>
<style>
.retract:after { content: '...'; position: absolute; bottom: 0; right: 0; }
.btn { cursor: pointer; color: #FFAD41; }
</style>

9. PDF 打印

使用 print-js 库实现 HTML 内容直接打印为 PDF。

<template>
  <div id="app">
    <div id="divPrint" class="mainbox print">
      <el-table :data="tableData" border style="width: 100%">
        <el-table-column prop="date" label="日期"></el-table-column>
        <el-table-column prop="name" label="姓名"></el-table-column>
        <el-table-column prop="address" label="地址"></el-table-column>
      </el-table>
    </div>
    <el-button @click="print">PDF 打印</el-button>
  </div>
</template>
<script>
import printJS from 'print-js';
export default {
  methods: {
    print() {
      printJS({
        printable: 'divPrint',
        type: 'html',
        targetStyles: ['*'],
        style: '@page {margin:0 10mm};',
        ignoreElements: ['no-print']
      });
    }
  }
};
</script>

10. 引导页

使用 driver.js 实现新功能引导蒙层。

<template>
  <div>
    <el-button type="primary" @click="driverD">引导</el-button>
  </div>
</template>
<script>
import { driver } from 'driver.js';
import 'driver.js/dist/driver.css';

const driverObj = driver({
  showProgress: true,
  steps: [
    { element: '#first', popover: { title: '第一步', description: '介绍功能 A' } },
    { element: '#second', popover: { title: '第二步', description: '介绍功能 B' } }
  ],
  allowClose: false,
  keyboardControl: false
});

export default {
  mounted() {
    if (!localStorage.Bj) {
      driverObj.drive();
      localStorage.setItem('Bj', 'true');
    }
  },
  methods: {
    driverD() { driverObj.drive(); }
  }
};
</script>

11. 回到顶部组件

封装 BackTop 组件，监听滚动事件控制显隐。

<template>
  <div ref="totop" class="totop" @click="scrollToTop" title="返回顶部">
    <svg viewBox="0 0 1024 1024"><path d="M512 225..." fill="#ffffff"/></svg>
  </div>
</template>
<script setup lang="ts">
import { ref, onMounted } from 'vue';
const totop = ref();
const scrollToTop = () => {
  window.scrollTo({ top: 0, behavior: 'smooth' });
};
onMounted(() => {
  window.onscroll = function() {
    const high = document.documentElement.scrollTop || document.body.scrollTop;
    totop.value.style.display = high >= 500 ? 'block' : 'none';
  };
});
</script>
<style scoped>
.totop { display: none; position: fixed; bottom: 120px; right: 80px; }
</style>

12. 锚点平滑滚动

点击导航栏平滑跳转至对应内容区域。

<template>
  <div class="nav">
    <a href="#Java" @click="goAnchor('#Java')">Java</a>
    <a href="#Python" @click="goAnchor('#Python')">Python</a>
  </div>
  <div id="Java" class="item">...</div>
</template>
<script>
export default {
  methods: {
    goAnchor(selector) {
      this.$el.querySelector(selector).scrollIntoView({
        behavior: 'smooth',
        block: 'start'
      });
    }
  }
};
</script>

13. 省市区选择器

基于 Element UI 级联选择器，配合地区数据插件。

npm install element-china-area-data -S

<template>
  <el-cascader size="large" :options="options" v-model="selectedOptions" />
</template>
<script>
import { regionData } from 'element-china-area-data';
export default {
  data() {
    return { options: regionData, selectedOptions: [] };
  }
};
</script>

14. 本地存储封装

封装带过期时间的 LocalStorage 和 SessionStorage 方法。

// utils/localStorage.js
export const localSet = (key, value, day) => {
  const d = new Date();
  const time = d.setHours(d.getHours() + (24 * day));
  window.localStorage.setItem(key, JSON.stringify({ value, time }));
};

export const localGet = (key) => {
  const obj = window.localStorage.getItem(key);
  if (obj) {
    const data = JSON.parse(obj);
    if (new Date().getTime() > data.time) {
      localStorage.removeItem(key);
      return null;
    }
    return data.value;
  }
  return '';
};

15. 拖拽 Dialog 指令

自定义 Vue 指令实现 Element UI Dialog 的拖拽功能。

directive/el-drag-dialog/drag.js

export default {
  bind(el, binding, vnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    const dragDom = el.querySelector('.el-dialog');
    dialogHeaderEl.style.cssText += ';cursor:move;';
    
    dialogHeaderEl.onmousedown = (e) => {
      const disX = e.clientX - dialogHeaderEl.offsetLeft;
      const disY = e.clientY - dialogHeaderEl.offsetTop;
      
      document.onmousemove = function(e) {
        let left = e.clientX - disX;
        let top = e.clientY - disY;
        dragDom.style.cssText += `;left:${left}px;top:${top}px;`;
      };
      document.onmouseup = function() {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    };
  }
};

main.js

import elDragDialog from '@/directive/el-drag-dialog/index';
Vue.directive('el-drag-dialog', elDragDialog);

以上这些片段覆盖了日常开发中高频出现的场景，建议收藏备用。实际使用时请根据项目实际情况调整参数和样式。