发明一个很好的演习做题网站 Codewars

都是本身做过的，先放本身的答案，再放本身以为不错的其他回复。

1. 将首字母放到背面并加上ay

pigIt('This is my string')转换成：pigIt('hisTay siay ymay tringsay')

• mine

  function pigIt(str){
      var _str = [];
      str.split(' ').forEach((_value) => _str.push(_value.slice(1)+_value.slice(0,1)+'ay'));
      return _str.join(' ');
  }

• others

  function pigIt(str){
      return str.replace(/(\w)(\w*)(\s|$)/g, "\$2\$1ay\$3")
  }

2. 数组变成字符串而且末了一个用&衔接

list([{name: 'Bart'},{name: 'Lisa'},{name: 'Maggie'},{name: 'Homer'},{name: 'Marge'}])转换成：'Bart, Lisa, Maggie, Homer & Marge'

• mine

  function list(names){
      if(names.length == 0)return '';
      let allname = [];
      names.forEach(function(_value){
          allname.push(_value.name);
      });
      let list = allname.join(",");
      var _index = list.lastIndexOf(",");
      list = list.replace(/,/g,function(a,b){
          return b == _index ? ' & ' : ', '
      });
      return list;
  }

• others

  function list(names) {
      var xs = names.map(p => p.name)
      var x = xs.pop()
      return xs.length ? xs.join(", ") + " & " + x : x || ""
  }

3. 将0移到数组背面且其他值在本来位置不排序

["a",0,"b",null,"c",0,"d",1,false,1,0,3,[],1,9,{},9,0]转换成：["a","b",null,"c","d",1,false,1,3,[],1,9,{},9,0,0,0,0]

• mine

  var moveZeros = function (arr) {
      let my_arr = arr.concat();
      let count = 0;
      arr.forEach(function(_value,_index){
          if(_value === 0){
              my_arr.push(...my_arr.splice(_index-count,1));
              count++;
          }
      });
      return my_arr;
  }

• others

  var moveZeros = function (arr) {
    return arr.filter(function(x) {return x !== 0}).concat(arr.filter(function(x) {return x === 0;}));
  }

4. 数组内奇数排序，偶数位置稳定

[5, 3, 2, 8, 1, 4]转换成：[1, 3, 2, 8, 5, 4]

• mine

  function sortArray(arr) {
      var myarr = [],
          myindex = [];
      arr.map(function(a,b){
          if(a%2 !== 0){
              console.log(a)
              myarr.push(a);
              myindex.push(b);
          }
      });
      myarr.sort((a,b) => a - b);
      myindex.map(function(a,b){
          arr[a] = myarr[b];
      });
      return arr;
  }

• others

  function sortArray(array) {
      const odd = array.filter((x) => x % 2).sort((a,b) => a - b);
      return array.map((x) => x % 2 ? odd.shift() : x);
  }

5. 字符串内里的数字排序

"is2 Thi1s T4est 3a"转换成："Thi1s is2 3a T4est"

• mine

  function order(words){
      var arr = words.split(' ');
      arr.sort(function(a,b){
          return /\d/.exec(a)[0] - /\d/.exec(b)[0];
      });
      return arr.join(' ');
  }

• others

  function order(words){
      return words.split(' ').sort(function(a, b){
          return a.match(/\d/) - b.match(/\d/);
      }).join(' ');
  }

6. 拆分数字并相乘直至个位数

给出参数39拆分：3*9 = 27, 2*7 = 14, 1*4=4(返回实行次数：三次)

• mine

  function persistence(num) {
      var count = 0;
      var Count = function(_num){
          var total = 1;
          if(_num.toString().length == 1){
              return count;
          }
          total = _num.toString().split('').map((a) => total = total * a).pop();
          count++;
          return Count(total);
      }
      return Count(num);
  }

• others

  const persistence = num => {
      return `${num}`.length > 1 ? 1 + persistence(`${num}`.split('').reduce((a, b) => (a * b)))
      : 0;
  }

7. 婚配暗码

六位以上暗码，最少一个数字、一个大写字母、一个小写字母

• mine

  function validate(password) {
      return /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])\w{6,}$/.test(password);
  }

• others

  function validate(password) {
    return  /^[A-Za-z0-9]{6,}$/.test(password) &&
            /[A-Z]+/           .test(password) &&
            /[a-z]+/           .test(password) &&
            /[0-9]+/           .test(password) ;
  }