[JavaScript知识库]「2022」字节-前端（互娱）笔试题

1.对数组原生方法的使用

① 题 目 ：

② 参考答案 ：

const arr1 = [10,9,8,7,6,5,4,3,2,1]
arr1.splice(2,1);

const arr2 = [10,9,8,7,6,5,4,3,2,1]
arr2.slice(0,2).concat(arr2.slice(3,10));

const arr3 = [10,9,8,7,6,5,4,3,2,1]
arr3.filter(res=>{
  return res!==arr3[2]
})
.....

2.简单正则的使用

① 题 目 ：

② 参考答案 ：

 function reg(str){
    let regexp = /^\d{3}-(\d{8}|010|10100)$/;
    return regexp.test(str);
  }
  reg('020-12345678'); => true
  reg('020-123456789'); => false

3.函数递归的使用

① 题 目 ：

② 参考答案 ：

const arr = [5, [[4, 3], 2, 1]];
function fun(arr) {
    if (Array.isArray(arr)) {
		var count = 0;
        arr.forEach((ele, index) => {

			if (Array.isArray(ele)){
				if (index === 0) {
					count += fun(ele); 
                } else {
					count -= fun(ele); 
                }
			} else {
				if (index === 0) {
					count += ele; 
				} else {
					count -= ele; 
				}	
			}
        }) 
	    
    }
   return count;
}
console.log(fun(arr));

4.通过vue/react 实现其效果---------------------------

① 题 目 ：

② 参考答案 ：(vue3)

//Toast.vue  ----------------------------------------------------------------
<template>
      <div class="Toast">
          <div v-if='typeof(content) ==="string"'>
               <p>{{content}}</p>
          </div>
          <div v-if='typeof(content) ==="object"'>
               <img :src="content.img?content.img:''">
               <p>{{content.text?content.text:''}}</p>
          </div>
      </div>
</template>
<script>  
import {toRefs} from 'vue';
export default {
    props: {
        content:{ type:Object||String},
        remove: { type:Function}
    },
    setup(props){
       setTimeout(props.remove, 3000 )
        return { ...toRefs(props)};
    }
    
}
</script>
<style  scoped>
    .Toast{
        width:200px;
        position: fixed;
        margin: 10px auto;
        top: 50%;
        left: calc(50% - 100px);
        background: #dddd;
        padding: 10px;
        border-radius: 10px;
    }
</style>
//---------------------------------------------------------------------------

// Toast.js -----------------------------------------------------------------
import { createApp } from "vue"
import Message from "./Toast.vue"
const Toast = res => {
    const res = res || '提示文字为空！';
    let messageNode = document.createElement("div")

    const app = createApp(Message, {
        content:res,
        remove() {  messageNode.remove() }
      })
    app.vm = app.mount(messageNode)
    document.body.appendChild(messageNode)   
 }
 export default Toast
 
 
 // 使用-------------------------------------------------------------------
import Toast from './xx/toast'
setup(){
    Toast('提示文字1，三秒钟消失！');
    Toast({
            test:'提示文字2',
            img:'https://xxx.com/aaa.jpeg'
          });
}

5.通过vue/react 实现其效果----------------------

① 题 目 ：

② 参考答案 ：(vue3)

//tree.vue 组件递归组件---------------------------------------------------------------
<template>
  <input type="text" v-if="index === 1" v-model="value" />
  <div style="width: 200px">
    <div v-for="item in Arr">
      <p
        :style="{
          marginLeft: (index - 1) * 12 + 'px',
          background: item.text === value ? 'red' : '',
        }"
      >
        <span @click="onoff(item.id)" v-if="item.children">
          {{ closeList.includes(item.id) ? "?" : "?" }}
        </span>
        {{ item.text }}
      </p>
      <div v-if="item.children && !closeList.includes(item.id)">
        <tree-list
          :Arr="item.children"
          :key="item.id"
          :index="index"
          :value="value"
        />
      </div>
    </div>
  </div>
</template>
<script>
import { reactive, toRefs, ref } from "vue";

export default {
  name: "tree-list",
  props: {
    Arr: { type: Array },
    index: { type: Number },
    value: { type: String },
  },
  setup(props) {
    let index = props.index ? props.index : 0;
    index += 1;
    console.log(props);
    const closeList = reactive([]);
    function onoff(id) {
      if (closeList.includes(id)) {
        closeList.splice(closeList.indexOf(id));
      } else {
        closeList.push(id);
      }
    }
    let value = ref(props.value) || ref("");

    return { ...toRefs(props), closeList, onoff, index, value };
  },
};
</script>

// 使用---------------------------------------------------
<template>
  <Tree :Arr="Arr" />
</template>

<script setup>
import Tree from "/@/components/tree.vue";

  components: { Tree },
  const Arr = [
      {
        id: "1",
        text: "菜单1",
        children: [
          {
            id: "2", 
            text: "菜单1-1",
            children: [
              {
                id: "3",
                text: "菜单1-1-1",
              },
              {
                id: "3", 
                text: "菜单1-1-2",
              },
            ],
          },
        ],
      },
      {
        id: "2",
        text: "菜单2",
      },
    ];
</script>