翻转字符串算法挑战

function reverseString(str) {
str = str.split("").reverse().join("")
return str;
}

reverseString("hello");

阶乘算法挑战

function factorialize(num) {
    let  sum = num ;
    if(num == 0){
       return 1 ; 
    }else{
       while(num > 1 ){
        sum *= (num-1) ;
        num -- ;
    } 
    }
    
    
return sum;
}

factorialize(0);

回文算法挑战

function palindrome(str) {
  str = str.replace(/[^a-zA-Zd]/g, "");
  return str.toLowerCase() == str
      .split("")
      .reverse()
      .join("")
      .toLowerCase();
}
palindrome("0_0 (: /- :) 0-0");

寻找最长的单词算法挑战

function findLongestWord(str) {
    str = str.split(" ");
    let len = str[0].length ;
    for(let i = 0 ; i < str.length ; i++){
        if(len <= str[i].length){
            len = str[i].length ;
        }
    }
    return len;
}

findLongestWord("The quick brown fox jumped over the lazy dog");

设置首字母大写算法挑战

function titleCase(str) {
    str = str.split(" ");
    for(let i = 0 ; i < str.length ; i++){
        str[i] =str[i].substring(0, 1).toUpperCase() + str[i].substring(1).toLowerCase(); 
    }
    str = str.join(" ");
return str;
}

titleCase("sHoRt AnD sToUt");

寻找数组中的最大值算法挑战

function largestOfFour(arr) {
    let newArr = [] ;
    for(let i = 0 ; i < arr.length ; i ++){
        let max = arr[i][0];
        for(let j = 0 ; j < arr[i].length ; j++){
            if(max <= arr[i][j]){
                max = arr[i][j];
            }
        }
    newArr.push(max);
}
return newArr;
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);

确认末尾字符算法挑战

function confirmEnding(str, target) {
// "Never give up and good luck will find you."
// -- Falcor
console.log(str,"|||",str.substring(str.length-target.length))
// return str.substring(str.length-target.length) == target;
return str.endsWith(target);
}

confirmEnding("Bastian", "n");

重复操作算法挑战

function repeat(str, num) {
// repeat after me
    if(num < 0){
        return ""
    }else{
        let newStr = "" ;
        for(let i = 0 ; i < num ; i++){
            newStr += str ;
        }
        return newStr;
    }
    
}

repeat("abc", 3);

字符串截取算法挑战

function truncate(str, num) {
// Clear out that junk in your trunk
    if(str.length <= num ){
        return str;
    }else{
       if(num <=3 ){
           return str.substring(0,num)+"...";
       } else{
           return str.substring(0,num-3)+"...";
       }
    }

}

truncate("Peter Piper picked a peck of pickled peppers", 14);

数组分割算法挑战

function chunk(arr, size) {
// Break it up.
    var index = 0;
    var newArray = [];

    while(index < arr.length) {
        newArray.push(arr.slice(index, index += size));
    }

    return newArray;
}

chunk(["a", "b", "c", "d"], 2);

数组截断算法挑战

function slasher(arr, howMany) {
// it doesn't always pay to be first
return arr.slice(howMany);
}

slasher([1, 2, 3], 2);

数组查询算法挑战

function mutation(arr) {
    let first = arr[0].toLowerCase();
    let target = arr[1].toLowerCase().split("") ;
    for(let i = 0 ; i < target.length ; i++){
        if(first.indexOf(target[i]) < 0 ){
            return false ;
        }
    }
    return true ;
        
}

mutation(["zyxwvutsrqponmlkjihgfedcba", "qrstu"]);

删除数组中特定值算法挑战

function bouncer(arr) {
// Don't show a false ID to this bouncer.
return arr.filter(params => Boolean(params));
}

function isBad(params){ 
    var result = Boolean(params); 
    return result; 
}

bouncer([7, "ate", "", false, 9]);

去除数组中任意多个值算法挑战

function destroyer(arr) {
  var args = [];
  for(var i = 1; i < arguments.length; i++){    //将待摧毁的值放入一个数组中，赋值给变量args
    args.push(arguments[i]);
  }
  var newArr=arr.filter(function(item){    //两个数组去重；
    return args.indexOf(item) === -1;
  });
  return newArr;
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3);

数组排序并插入值算法挑战

function where(arr, num) {
// Find my place in this sorted array.
arr.push(num);
arr = arr.sort(function(x,y){    //将num扔进arr中之后排序；
        return x-y;
       });
       console.log(arr);
return arr.indexOf(num);
}

where([3, 10, 5], 3);

位移密码算法挑战

function rot13(str) { // LBH QVQ VG!
    var newArr=[];
    for(var i=0;i<str.length;i++){
        var numbers=str.charCodeAt(i);    //使用charCodeAt()方法取得每个字符的Unicode值，并保存在变量numbers中；
        if(numbers<65||numbers>90){
            newArr.push(String.fromCharCode(numbers));
        }else if(numbers>77){
            newArr.push(String.fromCharCode(numbers-13));
        }else{
            newArr.push(String.fromCharCode(numbers+13));
        }
    }      //大写A-Z字母对应的Unicode值为65-90；通过判断，利用fromCharCode()将Unicode值又转换为字符；
    return newArr.join("");
}

// Change the inputs below to test
rot13("SERR PBQR PNZC");