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    3.0.0 • Public • Published


    Build Status npm install js-standard-style

    A library that wraps the Node.js crypto functions to create random floats and bounded integers with ease.

    Warning: I am not a cryptographer, or any sort of random number expert. An audit would be greatly appreciated.

    Version 3.0 of this module brings a new API and very different performance characteristics for integers; however it also removes bias which existed in older versions of this module.


    To install the module for use in your projects:

    npm install random-lib


    var rand = require('random-lib')
    var opts = {
      min: 1,
      max: 10,
      num: 10
    // get 10 random integers, between 1 and 10
    rand.ints(opts, function(err, results) {
      console.log(results) // [ 1, 1, 8, 9, 1, 4, 1, 6, 3, 8 ]
    // or, with promises
    rand.ints(opts).then(function(results) {
      console.log(results) // [ 2, 8, 4, 5, 2, 1, 7, 7, 8, 9 ]
    // or synchronously
    var results = rand.intsSync(opts)
    console.log(results) // [ 2, 1, 3, 8, 9, 7, 2, 4, 4, 7 ]

    Options are accepted, but are different if you're asking for floats or integers.


    Options are passed via an object; what's shown below are the defaults, and nothing is required.

    // for integers; what's shown are the defaults.
    var options = {
      num: 10,  // number of ints to receive
      min: 0,  // minimum bound (inclusive)
      max: Number.MAX_SAFE_INT,  // maximum bound (exclusive),
      unique: false  // receive only unique ints; only supported when async
    rand.ints(options, function(err, results) {
    //for floats; what's shown are the defaults.
    var options = {
      num: 10,  // number of floats to receive
      unique: false  // receive only unique floats; only supported when async
    rand.floats(options, function(err, results) {


    When calling any function, omitting a callback will cause the function to return a Promise.

    • ints([options], [callback (err, results)]): number[]
      Get an array of random integers.
    • int([options], [callback (err, result)]): number
      Convenience function to get a single random integer.
    • floats([options], [callback (err, results)]): number[]
      Get an array of random floats between 0 and 1.
    • float([options], [callback (err, results)]): number
      Convenience function to get a single random float between 0 and 1.

    Synchronous Methods

    Synchronous methods take the same options as their async counterparts, except for the unique option which is not supported while synchronous.

    • intsSync([options]): number[]
    • intSync([options]): number
    • floatsSync([options]): number[]
    • floatSync([options]): number


    • Using the synchronous interface calls crypto.randomBytes synchronously; please be sure to read the documentation for your Node.js version to understand the performance implications.


    Feel free to send pull requests! I'm not picky, but would like the following:

    1. Write tests for any new features, and do not break existing tests.
    2. Follow existing code style.
    3. Be sure to point out any changes that break API.
    4. Do not bump package.json version or add new dependencies without discussing in an issue first.


    See CHANGELOG for details.


    MIT. See LICENSE for details.


    npm i random-lib

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