data-randomizer

Installation

npm install --save data-randomizer

Usage

const SEED = 'My example Seed asdf 1234';

let Randomizer = require('data-randomizer');

let random = Randomizer.create(SEED);

let randomId = random.integer(10000, 20000);

let randomName = random.phrase(3);

let mockProduct = {
    id: randomId(),
    name: randomName()
};

Description

This module lets you create random data with arbitrary constraints.

It is pseudo-random, so it requires an arbitrary seed value to get started. Any string will do. The purpose of the seed is to maintain consistency from one run to the next. If you don't like the data being generated, then change the seed.

It is recursive, meaning that compound data structures will be treated as one iteration of the random sequence. The purpose of the recursion is to maintain consistency among multiple items, regardless of how deep the data goes. For example, if you generate an "atomic" value such as a number after a "compound" value such as an object, even if you add key-value pairs to the object, the subsequent number will not change. This is helpful when you want to keep as much of your existing structure as possible for a given seed.

Methods

(static) create(seed: String) -> DataRandomizer

Instantiates a randomizer.

let random = Randomizer.create('abc');

number(min: Number, max: Number, step?: Number) -> Function

Creates function that returns numbers between min (inclusive) and max (exclusive) at step intervals (default 0).

let randomHeight = random.number(25, 300)

let randomPrice = random.number(0.01, 999.99, 0.01)

integer(min: Number, max: Number) -> Function

Creates function that returns random integer between min (inclusive) and max (inclusive).

boolean(split?: Number) -> Function

Creates function that returns random boolean with split probability of being true (default 0.5).

phrase(wordCount: Number|Function) -> Function

Creates function that generates string with given number of words.

sentence() -> Function

Creates function that generates random string.

paragraph() -> Function

Creates function that generates random paragraph.

date(min: Date, max: Date) -> Function

Creates function that generates random Date in given range.

choice(list: Array) -> Function

Creates function that returns random item from list.

alternative(list: Array<Function>) -> Function

Creates function that randomly selects from the list of functions to invoke. This is useful to specify a union of multiple random type constraints.

array(count: Number|Function, randomItem: Function) -> Function

Creates function that generates array of random items. The count can be a constant number or a function that generates a random number.

object(template: Object) -> Function

Creates function that generates object with structure corresponding to template.

permutation(count: Number|Function, list: Array) -> Function

Creates function that generates array of items from list of length given by count (or the length of list, whichever is less). Each item in the resulting array will be distinct.

transform

All random values can be arbitrarily transformed. For example:

const randomAnswer = random.boolean().transform(b => b ? 'yes' : 'no');