写一个字符串转成驼峰的方法

var str = 'boder-bottom-color';

function test(str) {
    var arr = str.split('-');
    for(var i = 1; i<arr.length;i++ ) {
        arr[i] = arr[i].charAt(0).toUpperCase() + arr[i].substring(1);
    }
    return arr.join('-')
}
    
function test1(str) {
    var re = /-(\w)/g;
    return str.replace(re, function($0,$1) {
    
        return $1.toUpperCase();
    })
}

查找字符串中出现最多的字符和次数

var str = 'sdjksfssscfssdd';

function test(str) {
  var obj = {};
  var num = 0;
  var value = '';
  for(var i = 0; i<str.length; i++) {
      if(!obj[str[i]]) {
          obj[str[i]] = []
      }
      obj[str[i]].push(str[i]);
  }
  for(var attr in obj) {
      if(num < obj[attr].length) {
          num =  obj[attr].length;
          value =  obj[attr][0];
      }
  }
  return '最多的字符是'+ value + ', 出现了：' + num;
}
    
function test1(str) {
  var arr = str.split('');
  arr.sort();
  str = arr.join('');
  var num = 0;
  var value = '';

  var re = /(\w)\1+/g;

  str.replace(re, function ($0, $1) {
    console.log($0, $1)
    if (num < $0.length) {
      num = $0.length
      value = $1;
    }
  })
  return '最多的字符是' + value + ', 出现了：' + num;
}

如何给字符串加上千分符号

  var iNum =  str.length%3;
  var prev = '';
  var arr = [];
  var iNow = 0;
  var tmp = '';
  if(iNum !==0) {
    prev = str.substring(0,iNum)
    arr.push(prev)
  };
  str = str.substring(iNum)
  for(var i = 0; i<str.length;i++) {
    iNow++;
  
    tmp+= str[i]
    if(iNow == 3 && tmp) {
      arr.push(tmp);
      tmp = '';
      iNow = 0;
    }
  }
  return arr.join(',')
}

function test2(str) {
  var re = /(?=(?!\b)(\d{3})+$)/g;
  return str.replace(re,',')
}

返回一个只包含数字类型的数组

var str = 'js123ldka78sdassdfd653';

 var re =  /\d+/g;
 var arr = []; 
 str.replace(re,function($0,$1) {
   arr.push(Number($0))
 })

还别的方法，你来