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34 lines
909 B
34 lines
909 B
7 months ago
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//
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// ### function randomString (length)
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// #### @length {integer} The number of bits for the random base64 string returned to contain
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// randomString returns a pseude-random ASCII string (subset)
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// the return value is a string of length ⌈bits/6⌉ of characters
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// from the base64 alphabet.
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//
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function randomString(length) {
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let rand, i, ret, bits;
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const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-';
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const mod = 4;
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ret = '';
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// standard 4
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// default is 16
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bits = length * mod || 64;
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// in v8, Math.random() yields 32 pseudo-random bits (in spidermonkey it gives 53)
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while (bits > 0) {
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// 32-bit integer
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rand = Math.floor(Math.random() * 0x100000000);
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//we use the top bits
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for (i = 26; i > 0 && bits > 0; i -= mod, bits -= mod) {
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ret += chars[0x3f & (rand >>> i)];
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}
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}
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return ret;
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}
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module.exports = {
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randomString,
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};
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