Sharing of 4 functions for generating random numbers implemented in JS_Basic knowledge

The first method

Copy code The code is as follows:

/*
*@desc: Generate random string
*@remark: The toString method can receive a base as a parameter, and the base is capped from 2 to 36. If not specified, the default base is decimal
*/
function generateRandomAlphaNum(len) {
var rdmString = "";
for (; rdmString.length < len; rdmString = Math.random().toString(36).substr(2));
Return rdmString.substr(0, len);
}

The second method

Copy code The code is as follows:

//JS generates a GUID function, similar to NewID() in .net;
function S4() {
Return (((1 Math.random()) * 0x10000) | 0).toString(16).substring(1);
}

function NewGuid() {
Return (S4() S4() "-" S4() "-" S4() "-" S4() "-" S4() S4() S4());
}

The third method

Copy code The code is as follows:

//JS generates a GUID function, similar to NewID() in .net;
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;
}

The fourth method

Copy code The code is as follows:

/*
*@desc: Generate random string
*@demo:console.log(ranStr());
*/
;(function(){
//Numbers 0-9, uppercase letters, lowercase letters, ASCII or UNICODE encoding (decimal), 62 in total
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           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             var index = getBetweenRound(0,61);
              res.push(String.fromCharCode(charCodeArr[index]));
}
           return res.join('');
};

this.ranStr = ranStr;
})();