Four ways to generate UUID for JS

The globally unique identifier (guid,globally unique Identifier) is also known as the UUID (universally unique Identifier).

A GUID is a numeric identifier generated by the algorithm with a binary length of 128 bits. The format of the GUID is "Xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", where X is a 32-bit hexadecimal number in the range of 0-9 or a-f. Ideally, no computer or computer cluster will generate two identical GUIDs.

The total number of GUIDs reaches 2^128 (3.4x10^38), so the probability of randomly generating two identical GUIDs is very small, but not 0. The term GUID also sometimes refers to Microsoft's implementation of the UUID standard.

Algorithm 1

12345678910111213

functionuuid() {    var s = [];    varhexDigits = "0123456789abcdef";    for(vari = 0; i < 36; i++) {        s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);    }    s[14] = "4";  // bits 12-15 of the time_hi_and_version field to 0010    s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1);  // bits 6-7 of the clock_seq_hi_and_reserved to 01    s[8] = s[13] = s[18] = s[23] = "-";    varuuid = s.join("");    returnuuid;}

Algorithm 2

123456

functionguid() {    return‘xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx‘.replace(/[xy]/g, function(c) {        varr = Math.random()*16|0, v = c == ‘x‘? r : (r&0x3|0x8);        returnv.toString(16);    });}

Algorithm 3

123456

functionguid() {    functionS4() {       return (((1+Math.random())*0x10000)|0).toString(16).substring(1);    }    return(S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());}

Algorithm 4

12345678910111213141516171819202122232425262728

functionuuid(len, radix) {    varchars = ‘0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz‘.split(‘‘);    varuuid = [], i;    radix = radix || chars.length;    if(len) {      // Compact form      for(i = 0; i < len; i++) uuid[i] = chars[0 | Math.random()*radix];    } else{      // rfc4122, version 4 form      varr;      // rfc4122 requires these characters      uuid[8] = uuid[13] = uuid[18] = uuid[23] = ‘-‘;      uuid[14] = ‘4‘;      // Fill in random data.  At i==19 set the high bits of clock sequence as      // per rfc4122, sec. 4.1.5      for(i = 0; i < 36; i++) {        if(!uuid[i]) {          r = 0 | Math.random()*16;          uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];        }      }    }    returnuuid.join(‘‘);}

This can specify the length and cardinality. Like what

123456

// 8 character ID (base=2)uuid(8, 2)  //  "01001010"// 8 character ID (base=10)uuid(8, 10) // "47473046"// 8 character ID (base=16)uuid(8, 16) // "098F4D35"

Four ways to generate UUID for JS