基础练习

基础 笔记
js
Publish Date:   2022-01-19

[javascript基础测验题目链接](https://alidocs.dingtalk.com/i/team/O2RXDx4lJ6yRYXZj/docs/O2RXDQ0dD0o8ymZj# 「JavaScript基础测验」)

一，单项选择

  1. C✔️对象遍历通过for…in
  2. A✔️
  3. A✔️
  4. B✔️
  5. B✔️//函数提升优先级比变量优先级高
  6. D✔️

二，多项选择题

  1. ABC✔️
  2. ACD
  3. ACD
  4. ABCD
  5. AC
  6. ABC
  7. ABCD

三，编程

  1. //第一种
for (let i = 0; i < arr.length; i++) {
    var ran=Math.floor(Math.random()*arr.length);
    var temp=arr[ran];
    arr[ran]=arr[i];
    arr[i]=temp;
    console.log(arr[i]);
}
//第二种
var arr=[1,2,3,4,5,6,7];
var res=[],i=0;
while(arr.length>0){
    var ran=Math.floor(Math.random()*arr.length);
    res.push(arr[ran]);
    arr.splice(ran,1);
    console.log(res[i++]);
}
//第三种
var arr=[1,2,3,4,5,6,7];
arr.sort(function (){
    return Math.random()-0.5;
})
console.log(arr);

  2. ```javascript
    var x=10000000.111+””;
    var beg=x.indexOf(“.”)==-1?x.length:x.indexOf(“.”);
    var count=0;
    for(let i=beg-1;i>=0;i–){

    count++;
if(count%3==0)x=x.substring(0,i)+","+x.substring(i,x.length);

    }
    console.log(x);

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    3. ```javascript
       var s="aba";
       var n=s.length;
       function judge(s){
           for(var i=0;i<=n/2;i++){
               if(s.charAt(i)!=s.charAt(n-i-1)){
                   return false;
               }
           }
           return true;
       }
       console.log(judge(s));

  3. ```javascript
    Array.prototype.newArr=function (arr2){

    var arr1=[];
var res=[];
for (let i = 0; i < arr2.length; i++) {
    if(arr1.indexOf(arr2[i])!=-1){

    }else{
        arr1.push(arr2[i]);
        res.push(arr2[i]);
    }
}
return res;

    }
    console.log(new Array().newArr([1,1,1,2,3,4]));

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    5. 不太理解原型
    6. ```javascript
       var str1="asdasdsa1";
       function hasNum(str){
           for(let s of str){
               if(s>='0'&&s<='9')return true;
           }
           return false;
       }
       console.log(hasNum(str1));

  4. ```javascript
    function multipli(a,b){

    return a*b;

    }

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    8. ```javascript
       function remove(arr,item){
           var res=[];
           for(let n of arr){
               if(n!=item)res.push(n);
           }
           return res;
       }
       console.log(remove([1,2,3],1));

  5. ```javascript
    function toTwo(num){

    var res="";
while(num){
    res=parseInt(num%2).toString()+res;
    num=parseInt(num/2);
}
if(res.length<8){
    var remain="";
    for(var i=0;i<8-res.length;i++){
        remain+="0";
    }
    res=remain+res;
}
return res;

    }
    console.log(toTwo(11));

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    10. ```javascript
        var a=["1","2","3","4","5"];
        var index=0;
        function after(){
            console.log(a[index++]);
        }
        setInterval(after, 2000);

  6. ```javascript
    function mySort(arr){

    for(let i=0;i<arr.length-1;i++){
    for(let j=0;j<arr.length-i-1;j++){
        if(arr[j]>arr[j+1]){
            var temp=arr[j];
            arr[j]=arr[j+1];
            arr[j+1]=temp;
        }
    }
}
return arr;

    }
    console.log(mySort([1,3,2,4]));

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    12. ```javascript
        var s="20210107";
        var year=s.substring(0,4);
        var mon=s.substring(4,6);
        var day=s.substring(6,8);
        var res=year+"年"+mon+"月"+day;
        console.log(res);

  7. ```javascript
    var user=prompt(“请输入1,2,3 1:石头,2:剪刀,3:布”);
    var result=[‘石头’,’剪刀’,’布’];
    var robot=parseInt(Math.random()*3)+1;
    if(robot-user==1||robot==1&&user==3){

    console.log("你赢了！你出的是："+result[user-1]+"机器人出的是："+result[robot-1]);

    }else if(robot==user){

    console.log("平局！你出的是"+result[user-1]+"机器人出的是"+result[robot-1]);

    }else{

    console.log("你输了你出的是"+result[user-1]+"机器人出的是"+result[robot-1])

    }

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    14. ```javascript
        function xyRandom(x,y){
            return Math.floor(Math.random()*(y-x+1))+x;
        }
        console.log(xyRandom(3,1003));

  8. ```javascript
    var res=1,num=1;
    for(var i=0;i<64;i++){

    res*=2;
num+=res;

    }
    console.log(0.00001*num+”kg”);

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    16. ```javascript
        function seven(x){
            if(x%7==0)return false;
            while(x){
                if(x%10==7){
                    return false;
                }
                x=parseInt(x/10);
            }
            return true;
        }
        for(let i=0;i<=100;i++){
            if(seven(i))console.log(i);
        }

  9. ```javascript
    function sum(n){

    var res=1;
if(n%2==0){
    for(let i=2;i<=n;i+=2){
        res+=1/i;
    }
    return res;
}else{
    for(let i=3;i<=n;i+=2){
        res+=1/i;
    }
    return res;
}

    }
    console.log(sum(11));

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    18. ```javascript
        function isDivid(m,n){
            var num=0;
            var res=0;
            for(let i=1;i<=n;i++){
                num=num*10+i;
                if(i>=m&&num%3==0)res++;
            }
            return res;
        }
        console.log(isDivid(1,7));

  10. ```javascript
    不太会，自己瞎写的
    function getDataById(obj,target){

    if(typeof obj!="object")return ;
for(let key in obj){
    if(key[id]==target)return key;
    return getDataById(key,target);
}

    }

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    20. ```javascript
        function sum(n){
            var res=0;
            for(let i=1;i<=n;i++){
                var end=i;
                function huiwen(beg){
                    if(beg==end)return beg;
                    return ""+beg+huiwen(beg+1)+beg;
                }
                res+=parseInt(huiwen(1));
            }
            console.log(res);
        }
        sum(5);

  11. ```javascript
    function toTuo(s){

    var arr=s.split('');
var res=[];
for(var i=0;i<arr.length;i++){
    if(arr[i]=='-'){
        res.push(String.fromCharCode(s.charCodeAt(i+1)-32));i++;//String.fromCharCode(arr[i+1].charCodeAt(i+1)-32)
    }else{
        res.push(arr[i]);
    }
}
return res.join('');

    }
    console.log(toTuo(“asd-qwe-qwe”));

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    22. ```javascript
        function mySort(arr){
            var res=[];
            var num=[];
            for(let i=0;i<arr.length;i++){
                num.push(Object.keys(arr[i]).length);
            }
            for(var ii=0;ii<num.length-1;ii++){
                let max;
                max=0;
                var temp;
                var j;
                for(j=1;j<num.length-ii;j++){
                    if(num[j]>num[max]){
                        max=j;
                    }
                }
                temp=num[j-1];
                num[j-1]=num[max];
                num[max]=temp;
                temp=arr[j-1];
                arr[j-1]=arr[max];
                arr[max]=temp;
            }
            return arr;
        }
        var obj=[{a:1},{a:2,b:2,c:3},{a:3,b:2,c:4,d:5},{a:4,b:2}];
        console.log(mySort(obj));

  12. 不太会

  13. 不太会

  14. ```javascript
    function centerPad(str,len,clo){

    if(len<=str.length)return str;
var left=parseInt((len-str.length)/2);
var right=len-str.length-left;
var now=0,num=clo.length;
var lstr="",rstr="";
for(let i=0;i<left;i++){
    lstr+=clo[now%num];
    now++;
}
if(right!=left){
    rstr=lstr+clo[now%num];
}else{
    rstr=lstr;
}
return lstr+str+rstr;

    }
    console.log(centerPad(“hello”,15,”abcasd”));

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    26.
    27. ```javascript
        var a=[1,2,3,4];
        var res=[],one=0,two=0,thr=0,count=0;
        for(let i=0;i<a.length;i++){
            one=a[i];
            for(let j=0;j<a.length;j++){
                if(j==i)continue;
                two=one*10+a[j];
                for(let k=0;k<a.length;k++){
                    if(k==j||k==i)continue;
                    thr=two*10+a[k];
                    if(res.indexOf(thr)==-1){
                        count++;
                        res.push(thr);
                    }
                }
            }
        }
        console.log("数量为："+count+"，分别是：");
        console.log(res);


  15. ```javascript
    function myMoney(x){

    var mine=0;
if(x<=100000){
    return x*0.1;
}else if(x>100000&&x<200000){
    return 100000*0.1+(x-100000)*0.075;
}else if(x>=200000&&x<400000){
    return 100000*0.1+100000*0.075+(x-200000)*0.005;
}else if(x>400000&&x<600000){
    return 100000*0.1+100000*0.075+200000*0.005+(x-400000)*0.003;
}else if(x<1000000){
    return 100000*0.1+100000*0.075+200000*0.005+200000*0.003+(x-600000)*0.0015;
}else{
    return 100000*0.1+100000*0.075+200000*0.005+200000*0.003+400000*0.0015+(x-1000000)*0.001;
}

    }

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    29. ```javascript
        function remo(s){
            var res="";
            for (let c of s) {
                if(c!='a'&&
                   c!='e'&&
                   c!='i'&&
                   c!='o'&&
                   c!='u')res+=c;
            }
            return res;
        }
        console.log(remo("aeiosa"));

  16. ```javascript
    function condition(x){

    var a,b,c;
c=x%10;
b=parseInt(x/10)%10;
a=parseInt(x/100)%10;
if(c*c*c+b*b*b+a*a*a===x)return true;
return false;

    }
    for(let i=100;i<1000;i++){

    if(condition(i)){
    console.log(i);
}

    }

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    31. ```javascript
        var res=1;
        for (let i = 0; i < 9; i++) {
            res=(res+1)*2;
        }
        console.log(res);

  17. ```javascript
    function calcu(str){

    var num=0,letter=0,space=0,other=0;
for (let s of str) {
    if(s>='0'&&s<='9')num++;
    else if(s>='a'&&s<='z'||s>='A'&&s<='Z')letter++;
    else if(s==' ')space++;
    else other++;
}
console.log(num,letter,space,other);

    }
    calcu(‘ad123 ???’);

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    33. ```javascript
        console.log(
        "a->z,b->z,c->y"
        )

上课

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function fn(num){
    return num && num.toString().replace(/(\d)(?=(\d{3})+\.)/g,function (match){
    return match+',';
});
}
console.log(fn(1111111111.11));
Author: pkq
Link: http://gql.fit/2022/01/19/%E5%89%8D%E7%AB%AF/%E5%AD%A6%E4%B9%A0/%E5%94%AF%E5%88%9B%E5%89%8D%E7%AB%AF%E4%B8%8A%E8%AF%BE%E7%AC%94%E8%AE%B0/javascript%E5%9F%BA%E7%A1%80%E6%B5%8B%E9%AA%8C/
Reprint policy: All articles in this blog are used except for special statements CC BY 4.0 reprint policy. If reproduced, please indicate source pkq !
基础 笔记
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