mirror of https://github.com/jkjoy/sunpeiwen.git
85 lines
2.3 KiB
JavaScript
85 lines
2.3 KiB
JavaScript
/**
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* cuid.js
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* Collision-resistant UID generator for browsers and node.
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* Sequential for fast db lookups and recency sorting.
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* Safe for element IDs and server-side lookups.
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*
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* Extracted from CLCTR
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*
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* Copyright (c) Eric Elliott 2012
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* MIT License
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*/
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var fingerprint = require('./lib/fingerprint.js');
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var pad = require('./lib/pad.js');
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var getRandomValue = require('./lib/getRandomValue.js');
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var c = 0,
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blockSize = 4,
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base = 36,
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discreteValues = Math.pow(base, blockSize);
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function randomBlock () {
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return pad((getRandomValue() *
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discreteValues << 0)
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.toString(base), blockSize);
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}
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function safeCounter () {
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c = c < discreteValues ? c : 0;
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c++; // this is not subliminal
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return c - 1;
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}
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function cuid () {
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// Starting with a lowercase letter makes
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// it HTML element ID friendly.
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var letter = 'c', // hard-coded allows for sequential access
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// timestamp
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// warning: this exposes the exact date and time
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// that the uid was created.
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timestamp = (new Date().getTime()).toString(base),
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// Prevent same-machine collisions.
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counter = pad(safeCounter().toString(base), blockSize),
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// A few chars to generate distinct ids for different
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// clients (so different computers are far less
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// likely to generate the same id)
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print = fingerprint(),
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// Grab some more chars from Math.random()
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random = randomBlock() + randomBlock();
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return letter + timestamp + counter + print + random;
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}
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cuid.slug = function slug () {
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var date = new Date().getTime().toString(36),
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counter = safeCounter().toString(36).slice(-4),
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print = fingerprint().slice(0, 1) +
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fingerprint().slice(-1),
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random = randomBlock().slice(-2);
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return date.slice(-2) +
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counter + print + random;
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};
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cuid.isCuid = function isCuid (stringToCheck) {
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if (typeof stringToCheck !== 'string') return false;
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if (stringToCheck.startsWith('c')) return true;
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return false;
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};
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cuid.isSlug = function isSlug (stringToCheck) {
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if (typeof stringToCheck !== 'string') return false;
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var stringLength = stringToCheck.length;
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if (stringLength >= 7 && stringLength <= 10) return true;
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return false;
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};
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cuid.fingerprint = fingerprint;
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module.exports = cuid;
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