[JavaScript] crypto를 이용한 UUID (GUID) 만들기

!markdown

# JavaScript (자바스크립트)

JS에서 UUID를 어떻게 만들 수 있을까 알아보고 있었는데

아래는 StackOverFlow에서 따온 코드이다. 

간단하게 `UUID`를 만들 수 있다.

## 가독성 좋은 UUID 만들기 모듈 - by broofa

- 방법A

```js

function uuidv4() { 

    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); 

    }); 

} 

console.log(uuidv4());

```

- 방법 B

```js

function uuidv4() {

    return ([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g, c =>

        (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)

    );

}

```

방법 B는 IE11을 위해 `vendor prefix` 작업을 우선해야한다.

```js

var cryptoObj = window.crypto || window.msCrypto; // for IE 11

```

## 빠르고 최적화된 UUID - by Jeff Ward

아래로 내려갈 수록 `속도는 빨라`지는 반면 `가독성을 잃는다.`

- 원문: [https://stackoverflow.com/a/21963136/12873116](https://stackoverflow.com/a/21963136/12873116)

```js

function e1() {

  var u='',i=0;

  while(i++<36) {

    var c='xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'[i-1],r=Math.random()*16|0,v=c=='x'?r:(r&0x3|0x8);

    u+=(c=='-'||c=='4')?c:v.toString(16)

  }

  return u;

}

```

```js

function e2() {

  var u='',m='xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx',i=0,rb=Math.random()*0xffffffff|0;

  while(i++<36) {

    var c=m[i-1],r=rb&0xf,v=c=='x'?r:(r&0x3|0x8);

    u+=(c=='-'||c=='4')?c:v.toString(16);rb=i%8==0?Math.random()*0xffffffff|0:rb>>4

  }

  return u

}

```

```js

function e3() {

  var l='0123456789abcdef';

  var m='xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx';

  var u='',i=0,rb=Math.random()*0xffffffff|0;

  while(i++<36) {

    var c=m[i-1],r=rb&0xf,v=c=='x'?r:(r&0x3|0x8);

    u+=(c=='-'||c=='4')?c:l[v];rb=i%8==0?Math.random()*0xffffffff|0:rb>>4

  }

  return u

}

```

```js

function e4() {

  var h=['0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'];

  var k=['x','x','x','x','x','x','x','x','-','x','x','x','x','-','4','x','x','x','-','y','x','x','x','-','x','x','x','x','x','x','x','x','x','x','x','x'];

  var u='',i=0,rb=Math.random()*0xffffffff|0;

  while(i++<36) {

    var c=k[i-1],r=rb&0xf,v=c=='x'?r:(r&0x3|0x8);

    u+=(c=='-'||c=='4')?c:h[v];rb=i%8==0?Math.random()*0xffffffff|0:rb>>4

  }

  return u

}

```

```js

var lut = []; 

for (var i=0; i<256; i++) { lut[i] = (i<16?'0':'')+(i).toString(16); }

function e5() {

  var k=['x','x','x','x','-','x','x','-','4','x','-','y','x','-','x','x','x','x','x','x'];

  var u='',i=0,rb=Math.random()*0xffffffff|0;

  while(i++<20) {

    var c=k[i-1],r=rb&0xff,v=c=='x'?r:(c=='y'?(r&0x3f|0x80):(r&0xf|0x40));

    u+=(c=='-')?c:lut[v];rb=i%4==0?Math.random()*0xffffffff|0:rb>>8

  }

  return u

}

```

```js

var lut = []; 

for (var i=0; i<256; i++) { lut[i] = (i<16?'0':'')+(i).toString(16); }

function e6() {

  var k=['x','x','-','x','-','4','-','y','-','x','x','x'];

  var u='',i=0,rb=Math.random()*0xffffffff|0;

  while(i++<12) {

    var c=k[i-1],r=rb&0xffff,v=c=='x'?r:(c=='y'?(r&0x3fff|0x8000):(r&0xfff|0x4000));

    u+=(c=='-')?c:(lut[v>>8]+lut[v&0xff]);rb=i&1?rb>>16:Math.random()*0xffffffff|0

  }

  return u

}

```

```js

var lut = []; 

for (var i=0; i<256; i++) { lut[i] = (i<16?'0':'')+(i).toString(16); }

function e7() {

    var d0 = Math.random()*0xffffffff|0;

    var d1 = Math.random()*0xffffffff|0;

    var d2 = Math.random()*0xffffffff|0;

    var d3 = Math.random()*0xffffffff|0;

    return lut[d0&0xff]+lut[d0>>8&0xff]+lut[d0>>16&0xff]+lut[d0>>24&0xff]+'-'+

      lut[d1&0xff]+lut[d1>>8&0xff]+'-'+lut[d1>>16&0x0f|0x40]+lut[d1>>24&0xff]+'-'+

      lut[d2&0x3f|0x80]+lut[d2>>8&0xff]+'-'+lut[d2>>16&0xff]+lut[d2>>24&0xff]+

      lut[d3&0xff]+lut[d3>>8&0xff]+lut[d3>>16&0xff]+lut[d3>>24&0xff];

  }

```

- 속도비교

    [http://jsfiddle.net/jcward/7hyaC/3/](http://jsfiddle.net/jcward/7hyaC/3/)

### 참고

- Create GUID / UUID in JavaScript?: [https://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript](https://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript)

- Window.crypto: [https://developer.mozilla.org/ko/docs/Web/API/Window/crypto](https://developer.mozilla.org/ko/docs/Web/API/Window/crypto)