A node.js package to allow you apply the Counting Rule to Javascript object properties to generate mutations of an object for genetic algorithms or API endpoint testing
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Object Mutator

A small library that lets you generate mutations of a Javascript object at the property level. (See http://www.tumati.com/objectmutator-js-generating-all-or-some-subset-of-combinations-an-object-at-the-property-or-key-value-pair-level/.)


Documentation is lacking, but here's a quick example of usage:

let chromosome = {
    a: 0,
    b: 0,
    c: 0,
    d: "Unmutated property"

let mutationGroup = [
    { gene: "a", start: 5, checkRange: (i) => (i <= 10 ), step: (i) => i+1 },
    { gene: "b", start: 20, checkRange: (i) => ( i <= 30 ), step: (i) => i+2 },
    { gene: "c", start: -1, checkRange: (i) => ( i <= 3 ), step: (i) => i+1 }

let filteredMutationBag = new Mutator( chromosome, mutationGroup, (mutation) => { 
    return( mutation.a > 7 ) 
console.log( filteredMutationBag.mutations );

The mutations property above would contain every combination of 'chromosome' where:

    - 'a' ranges from 5 to 10, stepping by 1 *
    - 'b' ranges from 20 to 30, stepping by 2
    - 'c' ranges from -1 to 3, stepping by 1
    - 'd' remains the same in every object as it was passed in using the chromosome parameter

(* 'a' eventually gets filtered by the 'cullFunction', where the values that were generated 
with a from 5 to 7 are dropped.  This is just an example!  The cullFunction is useful for making 
sure that, in a new generation of objects, that certain objects are removed because of invalid 
relationships between properties.)


npm test


In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.