Summary of various algorithms for generating guids using JavaScript

A Globally Unique Identifier (GUID, Globally Unique IDentifier) is also called a UUID (Universally Unique Identifier ).

GUID is a 128-bit numeric identifier generated by an algorithm. The GUID format is "xxxxxxxx-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 generates two identical guids.

The total number of guids reaches 2 ^ 128 (3.4 × 10 ^ 38), so the probability of randomly generating two identical guids is very small, but not 0. The term GUID sometimes refers to Microsoft's UUID standard implementation.

Algorithm 1
Copy codeThe Code is as follows:

Function uuid (){
Var s = [];
Var hexDigits = "0123456789 abcdef ";
For (var I = 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] = "-";

Var uuid = s. join ("");
Return uuid;
}

Algorithm 2
Copy codeThe Code is as follows:
Function guid (){
Return 'xxxxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx '. replace (/[xy]/g, function (c ){
Var r = Math. random () * 16 | 0, v = c = 'X '? R: (r & 0x3 | 0x8 );
Return v. toString (16 );
});
}

Algorithm 3

Copy codeThe Code is as follows:
Function guid (){
Function S4 (){
Return (1 + Math. random () x 0x10000) | 0). toString (16). substring (1 );
}
Return (S4 () + S4 () + "-" + S4 () + "-" + S4 () + "-" + S4 () + "-" + S4 () + S4 () + S4 ());
}

Algorithm 4
Copy codeThe Code is as follows:
Function uuid (len, radix ){
Var chars = '0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz '. split ('');
Var uuid = [], 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
Var r;

// 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
// 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];
}
}
}

Return uuid. join ('');
}

You can specify the length and base number. For example
Copy codeThe Code is as follows:
// 8 character ID (base = 2)
Uuuid (8, 2) // "01001010"
// 8 character ID (base = 10)
Uuid (8, 10) // "47473046"
// 8 character ID (base = 16)
Uuid (8, 16) // "098F4D35"