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Genetic algorithm library written in JavaScript

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JSDarwin - Genetic Algorithm JS

Genetic algorithm library written in JavaScript

How To Use

The library lets you define specific functions for your particular application

Generating an individual

Define how to generate an individual. Function must return the constructed individual.


function generateIndividual() {
    let array = [];
    for(let i = 0; i < 10; i++) {
    return array;

Get the fitness for the individual

Define the fitness function. Function takes in an individual and returns its fitness value.


function getFitness(indv) {
    let fitness = 0;
    for(let i = 0; i < indv.length; i++) {
        fitness += indv[i] == 1 ? 1 : 0;
    return fitness;

Mutate an individual

Define how to mutate an individual. Function takes in an individual, mutates, and returns it.


function mutate(indv) {
    let mutatedIndex = Math.floor(Math.random() * indv.length);
    indv[mutatedIndex] = indv[mutatedIndex] == 1 ? 0 : 1;
    return indv;

(Optional) Breed two individuals

Define how to breed two individuals and produce a newborn. Function takes in two individuals and returns a new individual produced from both individuals

function breedFunction(parent0, parent1) {
    let newborn = parent0.slice();
    let randIndex = Math.round(Math.random() * parent1.length);
    newborn[randIndex] = parent1[randIndex];
    return newborn;


Create a toolbox that will hold your created functions

let toolbox = new Toolbox();
toolbox.genIndv = generateIndividual;
toolbox.getFitness = getFitness;
toolbox.mutate = mutate;

Set the goal fitness. If a larger fitness is desired than use Toolbox.fitnessMax; otherwise use Toolbox.fitnessMin.

toolbox.goalFitness = Toolbox.fitnessMax;

Define evolution parameters

let populationSize = 100;
let mutationProbability = .1;
let generations = 100;

Run evolution

Create Genetic Algorithm object and run evolution

let gen = new GeneticAlgorithm(toolbox, populationSize, mutationProbability, breedFunction);

let results = gen.evolve(generations); // Do something with the results

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