IOTConnect-Web/node_modules/ext/string/random.js
2024-05-09 09:49:52 +08:00

51 lines
1.4 KiB
JavaScript

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