SimpleFaker

This is a simplified Faker class that doesn't need any localized data to generate its output.

It only includes methods from:

• datatype
• date (without month and weekday)
• helpers (without fake)
• number
• string

import { simpleFaker } from '@faker-js/faker';
// const { simpleFaker } = require('@faker-js/faker');

// simpleFaker.seed(1234);

simpleFaker.number.int(10); // 4
simpleFaker.string.uuid(); // 'c50e1f5c-86e8-4aa9-888e-168e0a182519'

constructor

Creates a new instance of SimpleFaker.

In nearly any case you should use the prebuilt simpleFaker instances instead of the constructor.

Available since v8.1.0

Parameters

Name	Type	Default	Description
options	{ ... }	{}	The options to use.
options.randomizer?	Randomizer	generateMersenne53Randomizer()	The Randomizer to use. Specify this only if you want to use it to achieve a specific goal, such as sharing the same random generator with other instances/tools.
options.seed?	number		The initial seed to use. The seed can be used to generate reproducible values. Refer to the seed() method for more information. Defaults to a random seed.

Returns: SimpleFaker

function constructor(
  options: {
    randomizer?: Randomizer;
    seed?: number;
  } = {}
);

Examples

import { SimpleFaker } from '@faker-js/faker';
// const { SimpleFaker } = require('@faker-js/faker');

// create a SimpleFaker without any locale data
const customSimpleFaker = new SimpleFaker();

customSimpleFaker.helpers.arrayElement(['red', 'green', 'blue']); // 'green'
customSimpleFaker.number.int(10); // 4

Source

• View Source

seed

Sets the seed or generates a new one.

Please note that generated values are dependent on both the seed and the number of calls that have been made since it was set.

This method is intended to allow for consistent values in a tests, so you might want to use hardcoded values as the seed.

In addition to that it can be used for creating truly random tests (by passing no arguments), that still can be reproduced if needed, by logging the result and explicitly setting it if needed.

Available since v6.0.0

Parameters

Name	Type	Default	Description
seed?	number | number[]	randomSeed()	The seed or seed array to use.

Returns: number | number[]

function seed(seed?: number | number[]): number | number[];

Examples

// Consistent values for tests (using a number):
faker.seed(42)
faker.number.int(10); // 4
faker.number.int(10); // 8

faker.seed(42)
faker.number.int(10); // 4
faker.number.int(10); // 8

// Consistent values for tests (using an array):
faker.seed([42, 13, 17])
faker.number.int(10); // 4
faker.number.int(10); // 8

faker.seed([42, 13, 17])
faker.number.int(10); // 4
faker.number.int(10); // 8

// Random but reproducible tests:
// Simply log the seed, and if you need to reproduce it, insert the seed here
console.log('Running test with seed:', faker.seed());

See Also

• Reproducible Results
• faker.setDefaultRefDate(): For generating reproducible dates.

Source

• View Source

setDefaultRefDate

Sets the refDate source to use if no refDate date is passed to the date methods.

Available since v8.0.0

Parameters

Name	Type	Default	Description
dateOrSource	string | number | Date | (() => Date)	() => new Date()	The function or the static value used to generate the refDate date instance. The function must return a new valid Date instance for every call.

Returns: void

function setDefaultRefDate(
  dateOrSource: string | Date | number | (() => Date) = () => new Date()
): void;

Examples

faker.seed(1234);

// Default behavior
// faker.setDefaultRefDate();
faker.date.past(); // Changes based on the current date/time

// Use a static ref date
faker.setDefaultRefDate(new Date('2020-01-01'));
faker.date.past(); // Reproducible '2019-07-03T08:27:58.118Z'

// Use a ref date that changes every time it is used
let clock = new Date("2020-01-01").getTime();
faker.setDefaultRefDate(() => {
  clock += 1000; // +1s
  return new Date(clock);
});

faker.defaultRefDate() // 2020-01-01T00:00:01Z
faker.defaultRefDate() // 2020-01-01T00:00:02Z

See Also

• Reproducible Results
• faker.seed(): For generating reproducible values.

Source

• View Source