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October 1, 2022 19:56
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Code from video about generating UUIDs with JavaScript
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8" /> | |
| <meta http-equiv="X-UA-Compatible" content="IE=edge" /> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0" /> | |
| <title>Document</title> | |
| <style> | |
| html { | |
| font-size: large; | |
| font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', | |
| Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', | |
| sans-serif; | |
| font-weight: 300; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <button id="btnRun">Show Digits</button> | |
| <ol> | |
| <li>[1e7] + -1e3 + -4e3 + -8e3 + -1e11 converted to a string.</li> | |
| <li> | |
| For each 0, 1, or 8 in the original string. | |
| `10000000-1000-4000-8000-100000000000` | |
| </li> | |
| <li>new Uint8Array(1) creates 8-bit TypedArray [00000000]</li> | |
| <li> | |
| crypto.getRandomValues(TypedArray) fill TypedArray with a random | |
| number(s) 0-255. 1 per array index. | |
| </li> | |
| <li>Take first random number from TypedArray [0].</li> | |
| <li>c/4 = 0 || 0.25 || 2</li> | |
| <li>15 >> 0 || 0 || 2 = 1111 || 1111 || 0011</li> | |
| <li>random number from step 5, AND & 1111 || 1111 || 0011</li> | |
| <li>c (0000 | 0001 | 0101) XOR ^ result</li> | |
| </ol> | |
| <pre></pre> | |
| <code | |
| >let id = ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, (c) => ( | |
| c ^ (crypto.getRandomValues(new Uint8Array(1))[0] & (15 >> (c / 4))) | |
| ).toString(16) );</code | |
| > | |
| <script> | |
| const pre = document.querySelector('pre'); | |
| const btn = document.getElementById('btnRun'); | |
| btn.addEventListener('click', getDist); | |
| function getDist(ev) { | |
| let str = [1e7] + -1e3 + -4e3 + -8e3 + -1e11; | |
| pre.textContent = [1e7] + -1e3 + -4e3 + -8e3 + -1e11 + '\n'; | |
| let result = str.replace(/[018]/g, (c) => { | |
| let rand = crypto.getRandomValues(new Uint8Array(1))[0]; //random 0 -255 | |
| let shifted = 15 >> (c / 4); | |
| let ANDed = rand & shifted; | |
| let XORed = c ^ ANDed; | |
| let digit = XORed.toString(16); | |
| pre.textContent += `Hex digit is ${digit}\n`; | |
| // pre.textContent += `************** \n`; | |
| return digit; | |
| }); | |
| pre.textContent += 'crypto.getRandomValues() ' + result + '\n'; | |
| //OR the newer randomUUID method | |
| if (crypto && 'randomUUID' in crypto) { | |
| pre.textContent += | |
| 'NEW crypto.randomUUID() ' + crypto.randomUUID() + '\n'; | |
| } | |
| } | |
| </script> | |
| </body> | |
| </html> |
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| import crypto from 'crypto'; | |
| if (crypto) { | |
| let id; | |
| if (false && 'randomUUID' in crypto) { | |
| console.log('randomUUID'); | |
| id = crypto.randomUUID(); | |
| } else { | |
| console.log('getRandomValues'); | |
| id = ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, (c) => | |
| ( | |
| c ^ | |
| (crypto.webcrypto.getRandomValues(new Uint8Array(1))[0] & | |
| (15 >> (c / 4))) | |
| ).toString(16) | |
| ); | |
| //in the browser it is crypto.getRandomValues(new Uint8Array(1))[0] | |
| } | |
| console.log(id); | |
| } else { | |
| console.log('no support for crypto'); | |
| } |
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