seed-random - npm Package Compare versions

Comparing version 1.0.1 to 2.2.0

component.json

@@ -5,3 +5,3 @@ {
   "description": "Generate random numbers with a seed, useful for reproducible tests",
-  "version": "1.0.1",
+  "version": "2.2.0",
   "keywords": [],
@@ -8,0 +8,0 @@ "dependencies": {},

index.js

@@ -0,9 +1,20 @@
+'use strict';
+
 var width = 256;// each RC4 output is 0 <= x < 256
 var chunks = 6;// at least six RC4 outputs for each double
-var significance = 52;// there are 52 significant digits in a double
+var digits = 52;// there are 52 significant digits in a double
+var pool = [];// pool: entropy pool starts empty
+var GLOBAL = typeof global === 'undefined' ? window : global;
 
-var overflow, startdenom; //numbers
+//
+// The following constants are related to IEEE 754 limits.
+//
+var startdenom = Math.pow(width, chunks),
+    significance = Math.pow(2, digits),
+    overflow = significance * 2,
+    mask = width - 1;
 
 
 var oldRandom = Math.random;
+
 //
@@ -13,18 +24,23 @@ // seedrandom()
 //
-module.exports = function seedrandom(seed, overRideGlobal) {
-  if (!seed) {
-    if (overRideGlobal) {
-      Math.random = oldRandom;
-    }
-    return oldRandom;
+module.exports = function(seed, options) {
+  if (options && options.global === true) {
+    options.global = false;
+    Math.random = module.exports(seed, options);
+    options.global = true;
+    return Math.random;
   }
+  var use_entropy = (options && options.entropy) || false;
   var key = [];
-  var arc4;
 
   // Flatten the seed string or build one from local entropy if needed.
-  seed = mixkey(flatten(seed, 3), key);
+  var shortseed = mixkey(flatten(
+    use_entropy ? [seed, tostring(pool)] :
+    0 in arguments ? seed : autoseed(), 3), key);
 
   // Use the seed to initialize an ARC4 generator.
-  arc4 = new ARC4(key);
+  var arc4 = new ARC4(key);
 
+  // Mix the randomness into accumulated entropy.
+  mixkey(tostring(arc4.S), pool);
+
   // Override Math.random
@@ -35,6 +51,6 @@
 
-  function random() {  // Closure to return a random double:
-    var n = arc4.g(chunks);             // Start with a numerator n < 2 ^ 48
-    var d = startdenom;                 //   and denominator d = 2 ^ 48.
-    var x = 0;                          //   and no 'extra last byte'.
+  return function() {         // Closure to return a random double:
+    var n = arc4.g(chunks),             // Start with a numerator n < 2 ^ 48
+        d = startdenom,                 //   and denominator d = 2 ^ 48.
+        x = 0;                          //   and no 'extra last byte'.
     while (n < significance) {          // Fill up all significant digits by
@@ -51,10 +67,7 @@ n = (n + x) * width;              //   shifting numerator and
     return (n + x) / d;                 // Form the number within [0, 1).
-  }
-  random.seed = seed;
-  if (overRideGlobal) {
-    Math['random'] = random;
-  }
+  };
+};
 
-  // Return the seed that was used
-  return random;
+module.exports.resetGlobal = function () {
+  Math.random = oldRandom;
 };
@@ -74,6 +87,4 @@
 function ARC4(key) {
-  var t, u, me = this, keylen = key.length;
-  var i = 0, j = me.i = me.j = me.m = 0;
-  me.S = [];
-  me.c = [];
+  var t, keylen = key.length,
+      me = this, i = 0, j = me.i = me.j = 0, s = me.S = [];
 
@@ -84,33 +95,24 @@ // The empty key [] is treated as [0].
   // Set up S using the standard key scheduling algorithm.
-  while (i < width) { me.S[i] = i++; }
+  while (i < width) {
+    s[i] = i++;
+  }
   for (i = 0; i < width; i++) {
-    t = me.S[i];
-    j = lowbits(j + t + key[i % keylen]);
-    u = me.S[j];
-    me.S[i] = u;
-    me.S[j] = t;
+    s[i] = s[j = mask & (j + key[i % keylen] + (t = s[i]))];
+    s[j] = t;
   }
 
   // The "g" method returns the next (count) outputs as one number.
-  me.g = function getnext(count) {
-    var s = me.S;
-    var i = lowbits(me.i + 1); var t = s[i];
-    var j = lowbits(me.j + t); var u = s[j];
-    s[i] = u;
-    s[j] = t;
-    var r = s[lowbits(t + u)];
-    while (--count) {
-      i = lowbits(i + 1); t = s[i];
-      j = lowbits(j + t); u = s[j];
-      s[i] = u;
-      s[j] = t;
-      r = r * width + s[lowbits(t + u)];
+  (me.g = function(count) {
+    // Using instance members instead of closure state nearly doubles speed.
+    var t, r = 0,
+        i = me.i, j = me.j, s = me.S;
+    while (count--) {
+      t = s[i = mask & (i + 1)];
+      r = r * width + s[mask & ((s[i] = s[j = mask & (j + t)]) + (s[j] = t))];
     }
-    me.i = i;
-    me.j = j;
+    me.i = i; me.j = j;
     return r;
-  };
-  // For robust unpredictability discard an initial batch of values.
-  // See http://www.rsa.com/rsalabs/node.asp?id=2009
-  me.g(width);
+    // For robust unpredictability discard an initial batch of values.
+    // See http://www.rsa.com/rsalabs/node.asp?id=2009
+  })(width);
 }
@@ -122,16 +124,10 @@
 //
-/** @param {Object=} result 
-  * @param {string=} prop
-  * @param {string=} typ */
-function flatten(obj, depth, result, prop, typ) {
-  result = [];
-  typ = typeof(obj);
-  if (depth && typ == 'object') {
+function flatten(obj, depth) {
+  var result = [], typ = (typeof obj)[0], prop;
+  if (depth && typ == 'o') {
     for (prop in obj) {
-      if (prop.indexOf('S') < 5) {    // Avoid FF3 bug (local/sessionStorage)
-        try { result.push(flatten(obj[prop], depth - 1)); } catch (e) {}
-      }
+      try { result.push(flatten(obj[prop], depth - 1)); } catch (e) {}
     }
   }
-  return (result.length ? result : obj + (typ != 'string' ? '\0' : ''));
+  return (result.length ? result : typ == 's' ? obj : obj + '\0');
 }
@@ -144,27 +140,41 @@
 //
-/** @param {number=} smear 
-  * @param {number=} j */
-function mixkey(seed, key, smear, j) {
-  seed += '';                         // Ensure the seed is a string
-  smear = 0;
-  for (j = 0; j < seed.length; j++) {
-    key[lowbits(j)] =
-      lowbits((smear ^= key[lowbits(j)] * 19) + seed.charCodeAt(j));
+function mixkey(seed, key) {
+  var stringseed = seed + '', smear, j = 0;
+  while (j < stringseed.length) {
+    key[mask & j] =
+      mask & ((smear ^= key[mask & j] * 19) + stringseed.charCodeAt(j++));
   }
-  seed = '';
-  for (j in key) { seed += String.fromCharCode(key[j]); }
-  return seed;
+  return tostring(key);
 }
 
 //
-// lowbits()
-// A quick "n mod width" for width a power of 2.
+// autoseed()
+// Returns an object for autoseeding, using window.crypto if available.
 //
-function lowbits(n) { return n & (width - 1); }
+/** @param {Uint8Array=} seed */
+function autoseed(seed) {
+  try {
+    GLOBAL.crypto.getRandomValues(seed = new Uint8Array(width));
+    return tostring(seed);
+  } catch (e) {
+    return [+new Date, GLOBAL, GLOBAL.navigator && GLOBAL.navigator.plugins,
+            GLOBAL.screen, tostring(pool)];
+  }
+}
 
 //
-// The following constants are related to IEEE 754 limits.
+// tostring()
+// Converts an array of charcodes to a string
 //
-startdenom = Math.pow(width, chunks);
-significance = Math.pow(2, significance);
-overflow = significance * 2;
+function tostring(a) {
+  return String.fromCharCode.apply(0, a);
+}
+
+//
+// When seedrandom.js is loaded, we immediately mix a few bits
+// from the built-in RNG into the entropy pool.  Because we do
+// not want to intefere with determinstic PRNG state later,
+// seedrandom will not call Math.random on its own again after
+// initialization.
+//
+mixkey(Math.random(), pool);

package.json

 {
   "name": "seed-random",
-  "version": "1.0.1",
+  "version": "2.2.0",
   "description": "Generate random numbers with a seed, useful for reproducible tests",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "node test/index.js"
   },
@@ -13,4 +13,4 @@ "repository": {
   },
-  "author": "",
+  "author": "ForbesLindesay",
   "license": "MIT"
 }

Readme.md

@@ -1,10 +0,12 @@
-
 # seed-random
 
-  Generate random numbers with a seed, useful for reproducible tests
+Generate random numbers with a seed, useful for reproducible tests
 
+
+[![build status](https://secure.travis-ci.org/ForbesLindesay/seed-random.png?branch=master)](http://travis-ci.org/ForbesLindesay/seed-random)
+[![Dependency Status](https://gemnasium.com/ForbesLindesay/seed-random.png)](https://gemnasium.com/ForbesLindesay/seed-random)
+[![NPM version](https://badge.fury.io/js/seed-random.png)](http://badge.fury.io/js/seed-random)
+
 ## Installation
 
-    $ component install ForbesLindesay/seed-random
-
     $ npm install seed-random
@@ -14,24 +16,30 @@
 
-  ```javascript
-  var seed = require('seed-random');
+```javascript
+var assert = require('assert');
+var seed = require('../');
 
-  var trueRandomA = seed();
-  var trueRandomB = seed();
-  trueRandomA() != trueRandomB(); //almost always true
+var trueRandomA = seed();
+var trueRandomB = seed();
+assert(trueRandomA() != trueRandomB());
 
-  var fakeRandomA = seed('foo');
-  var fakeRandomB = seed('foo');
-  fakeRandomA() == fakeRandomB(); //always true
+var fakeRandomA = seed('foo');
+var fakeRandomB = seed('foo');
+assert(fakeRandomA() == fakeRandomB());
 
-  seed('foo', true);//over-ride global Math.random
-  var numA = Math.random();
-  seed('foo', true);
-  var numB = Math.random();
-  numA == numB;//always true
+var fakeRandomC = seed('foo', {entropy: true});
+var fakeRandomD = seed('foo', {entropy: true});
+assert(fakeRandomC() != fakeRandomD());
 
-  seed(undefined, true);//reset to default Math.random
-  ```
 
+seed('foo', {global: true});//over-ride global Math.random
+var numA = Math.random();
+seed('foo', {global: true});
+var numB = Math.random();
+assert(numA == numB);//always true
+
+seed.resetGlobal();//reset to default Math.random
+```
+
 ## License
 
-  MIT
+MIT

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Improved metrics

Total package byte prevSize

10855

69.77%

Number of package files

9

50%

Lines of code

182

15.19%

Number of low maintenance alerts

2

-33.33%

Number of low quality alerts

1

-50%

Number of lines in readme file

45

21.62%

Worsened metrics

Number of low license alerts

1

Infinity%

No dependency changes