JavaScript生成随机数的4种自定义函数分享

/*

*@desc:生成随机字符串

*@remark:toString方法可以接收一个基数作为参数的原理，这个基数从2到36封顶。如果不指定，默认基数是10进制

*/

function generateRandomAlphaNum(len) {

  var rdmString = "";

  for (; rdmString.length < len; rdmString += Math.random().toString(36).substr(2));

  return rdmString.substr(0, len);

}

//JS生成GUID函数,类似.net中的NewID(); 

function S4() {

  return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);

}



function NewGuid() {

  return (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());

}

//JS生成GUID函数,类似.net中的NewID(); 

function newGuid() {

  var guid = "";

  for (var i = 1; i <= 32; i++) {

    var n = Math.floor(Math.random() * 16.0).toString(16);

    guid += n;

    if ((i == 8) || (i == 12) || (i == 16) || (i == 20))

      guid += "-";

  }

  return guid;

}

/*

*@desc:生成随机字符串

*@demo:console.log(ranStr());

*/

;(function(){

  //数字0-9，大写字母，小写字母，ASCII或UNICODE编码（十进制），共62个

  var charCodeIndex = [[48,57],[65,90],[97,122]];

  var charCodeArr = [];



  function getBetweenRound(min,max){

    return Math.floor(min+Math.random()*(max-min));

  };



  function getCharCode(){

    for(var i=0,len=3;i<len;i++){

      var thisArr = charCodeIndex[i];

      for(var j=thisArr[0],thisLen=thisArr[1];j<=thisLen;j++){

        charCodeArr.push(j);

      }

    }

  }



  function ranStr(slen){

    slen = slen || 20;

    charCodeArr.length<62 && getCharCode();



    var res = [];

    for(var i=0;i<slen;i++){

      var index = getBetweenRound(0,61);

      res.push(String.fromCharCode(charCodeArr[index]));

    }

    return res.join(');

  };



  this.ranStr = ranStr;

})();