Summary of various algorithms for generating GUID using JavaScript_javascript skills

Globally unique identifier (GUID, Globally Unique Identifier) ​​is also called UUID (Universally Unique IDentifier).

GUID is an algorithmically generated numeric identifier with a binary length of 128 bits. The format of the GUID is "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", where x is a 32-digit hexadecimal number in the range of 0-9 or a-f. In an ideal world, no two computers or clusters of computers will generate the same GUID.

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

Algorithm 1

Copy code The code is as follows:

function uuid() {
var s = [];
var hexDigits = "0123456789abcdef";
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 code The code is as follows:

function guid() {
Return 'xxxxxxxx-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);

Copy code

The code is as follows:function guid() { function S4() { return (((1 Math.random())*0x10000)|0).toString(16).substring(1); }

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

}


Algorithm 4

Copy code

The code is as follows:function uuid(len, radix) { var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnop qrstuvwxyz'. 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 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];
}
}
}

return uuid.join('');
}


This can specify the length and base. For example,

Copy code

The code is as follows:// 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"