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简介:
UUID(Universally Unique IDentifier) 全局惟一标识符。
UUID 是一种由算法生成的二进制长度为 128 位的数字标识符。UUID
的格局为“xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx”,其中的 x 是 0-9 或 a-f
范畴内的一个 32 位十六进制数。在现实状况下,任何计算机和计算机集群都不会生成两个雷同的 UUID。
1. 第一种
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);
});
}
guid() // "a1ca0f7b-51bd-4bf3-a5d5-6a74f6adc1c7"
2. 第二种
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;
}
uuid() // "ffb7cefd-02cb-4853-8238-c0292cf988d5"
3. 第三种
function guid2() {function S4() {return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
}
return (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());
}
guid2() // "748eea29-f842-4af9-a552-e1e1aa3ed979"
4. 第四种
// 指定长度和基数
function uuid2(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 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('');
}
uuid2(16, 16) // "277571702EE33E11"
5. 第五种
阐明: 生成 32 位 UUID 办法
function uuid() {var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 32; 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;
}
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