50 lines
1.4 KiB
JavaScript
50 lines
1.4 KiB
JavaScript
"use strict";
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var isObject = require("type/object/is")
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, ensureNaturalNumber = require("type/natural-number/ensure")
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, ensureString = require("type/string/ensure");
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var generated = Object.create(null), random = Math.random, uniqTryLimit = 100;
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var getChunk = function () { return random().toString(36).slice(2); };
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var getString = function (length, charset) {
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var str;
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if (charset) {
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var charsetLength = charset.length;
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str = "";
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for (var i = 0; i < length; ++i) {
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str += charset.charAt(Math.floor(Math.random() * charsetLength));
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}
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return str;
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}
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str = getChunk();
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if (length === null) return str;
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while (str.length < length) str += getChunk();
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return str.slice(0, length);
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};
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module.exports = function (/* options */) {
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var options = arguments[0];
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if (!isObject(options)) options = {};
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var length = ensureNaturalNumber(options.length, { "default": 10 })
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, isUnique = options.isUnique
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, charset = ensureString(options.charset, { isOptional: true });
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var str = getString(length, charset);
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if (isUnique) {
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var count = 0;
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while (generated[str]) {
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if (++count === uniqTryLimit) {
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throw new Error(
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"Cannot generate random string.\n" +
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"String.random is not designed to effectively generate many short and " +
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"unique random strings"
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);
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}
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str = getString(length);
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}
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generated[str] = true;
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}
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return str;
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};
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