FakerHelpers
Module with various helper methods that transform the method input rather than returning values from locales. The transformation process may call methods that use the locale data.
- Array Element
- Array Elements
- Maybe
- Mustache
- Object Key
- Object Value
- Regexp Style String Parse
- Repeat String
- Replace Credit Card Symbols
- Replace Symbol With Number
- Replace Symbols
- Shuffle
- Slugify
- Unique Array
Array Element
Returns random element from the given array.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | The type of the entries to pick from. | ||
| array | readonly T[] | ['a', 'b', 'c'] | Array to pick the value from. |
Returns: T
faker.helpers.arrayElement<T>(array: readonly T[] = ['a', 'b', 'c']): T
faker.helpers.arrayElement() // => "b"
faker.helpers.arrayElement(['cat', 'dog', 'mouse']) // 'dog'
Array Elements
Returns a subset with random elements of the given array in random order.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | The type of the entries to pick from. | ||
| array | readonly T[] | ['a', 'b', 'c'] | Array to pick the value from. |
| count? | number | Number of elements to pick. When not provided, random number of elements will be picked. When value exceeds array boundaries, it will be limited to stay inside. |
Returns: T[]
faker.helpers.arrayElements<T>(array: readonly T[] = ['a', 'b', 'c'], count?: number): T[]
faker.helpers.arrayElements() // => ["c","b"]
faker.helpers.arrayElements(['cat', 'dog', 'mouse']) // ['mouse', 'cat']
faker.helpers.arrayElements([1, 2, 3, 4, 5], 2) // [4, 2]
Maybe
Returns the result of the callback if the probability check was successful, otherwise undefined.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | The type of result of the given callback. | ||
| callback | () => T | The callback to that will be invoked if the probability check was successful. | |
| options | { ... } | {} | The options to use. |
| options.probability? | number | 0.5 | The probability ( |
Returns: T
faker.helpers.maybe<T>(callback: () => T, options: {
probability: number
} = {}): T
faker.helpers.maybe(() => 'Hello World!') // 'Hello World!'
faker.helpers.maybe(() => 'Hello World!', { probability: 0.1 }) // undefined
faker.helpers.maybe(() => 'Hello World!', { probability: 0.9 }) // 'Hello World!'
Mustache
Replaces the {{placeholder}} patterns in the given string mustache style.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| str | string | The template string to parse. | |
| data | Record<string, (substring: string, args: any[]) => string | string> | The data used to populate the placeholders.
This is a record where the key is the template placeholder,
whereas the value is either a string or a function suitable for |
Returns: string
faker.helpers.mustache(str: string, data: Record<string, (substring: string, args: any[]) => string | string>): string
faker.helpers.mustache() // => ""
faker.helpers.mustache('I found {{count}} instances of "{{word}}".', {
count: () => `${faker.datatype.number()}`,
word: "this word",
}) // 'I found 57591 instances of "this word".'
Object Key
Returns a random key from given object or undefined if no key could be found.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | Record<string, unknown> | Missing | |
| object | T | The object to be used. |
Returns: keyof T
faker.helpers.objectKey<T>(object: T): keyof T
faker.helpers.objectKey({ myProperty: 'myValue' }) // 'myProperty'
Object Value
Returns a random value from given object or undefined if no key could be found.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | Record<string, unknown> | Missing | |
| object | T | The object to be used. |
Returns: T[keyof T]
faker.helpers.objectValue<T>(object: T): T[keyof T]
faker.helpers.objectValue({ myProperty: 'myValue' }) // 'myValue'
Regexp Style String Parse
Replaces the regex like expressions in the given string with matching values.
Supported patterns:
.{times}=> Repeat the character exactlytimestimes..{min,max}=> Repeat the charactermintomaxtimes.[min-max]=> Generate a number between min and max (inclusive).
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '' | The template string to to parse. |
Returns: string
faker.helpers.regexpStyleStringParse(string: string = ''): string
faker.helpers.regexpStyleStringParse() // => ""
faker.helpers.regexpStyleStringParse() // ''
faker.helpers.regexpStyleStringParse('#{5}') // '#####'
faker.helpers.regexpStyleStringParse('#{2,9}') // '#######'
faker.helpers.regexpStyleStringParse('[500-15000]') // '8375'
faker.helpers.regexpStyleStringParse('#{3}test[1-5]') // '###test3'
Repeat String
Repeats the given string the given number of times.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '' | The string to repeat. |
| num | number | 0 | The number of times to repeat it. |
Returns: string
faker.helpers.repeatString(string: string = '', num: number = 0): string
faker.helpers.repeatString() // => ""
faker.helpers.repeatString('Hello world! ') // ''
faker.helpers.repeatString('Hello world! ', 1) // 'Hello world! '
faker.helpers.repeatString('Hello world! ', 2) // 'Hello world! Hello world! '
Replace Credit Card Symbols
Replaces the symbols and patterns in a credit card schema including Luhn checksum.
This method supports both range patterns [4-9] as well as the patterns used by replaceSymbolWithNumber().
L will be replaced with the appropriate Luhn checksum.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '6453-####-####-####-###L' | The credit card format pattern. |
| symbol | string | '#' | The symbol to replace with a digit. |
Returns: string
faker.helpers.replaceCreditCardSymbols(string: string = '6453-####-####-####-###L', symbol: string = '#'): string
faker.helpers.replaceCreditCardSymbols() // => "6453-5578-6858-4663-4283"
faker.helpers.replaceCreditCardSymbols() // '6453-4876-8626-8995-3771'
faker.helpers.replaceCreditCardSymbols('1234-[4-9]-##!!-L') // '1234-9-5298-2'
Replace Symbol With Number
Parses the given string symbol by symbol and replaces the placeholders with digits (0 - 9).
! will be replaced by digits >=2 (2 - 9).
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '' | The template string to parse. |
| symbol | string | '#' | The symbol to replace with digits. |
Returns: string
faker.helpers.replaceSymbolWithNumber(string: string = '', symbol: string = '#'): string
faker.helpers.replaceSymbolWithNumber() // => ""
faker.helpers.replaceSymbolWithNumber() // ''
faker.helpers.replaceSymbolWithNumber('#####') // '04812'
faker.helpers.replaceSymbolWithNumber('!####') // '27378'
faker.helpers.replaceSymbolWithNumber('Your pin is: !####') // '29841'
Replace Symbols
Parses the given string symbol by symbols and replaces the placeholder appropriately.
#will be replaced with a digit (0-9).?will be replaced with an upper letter ('A' - 'Z')- and
*will be replaced with either a digit or letter.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '' | The template string to parse. |
Returns: string
faker.helpers.replaceSymbols(string: string = ''): string
faker.helpers.replaceSymbols() // => ""
faker.helpers.replaceSymbols() // ''
faker.helpers.replaceSymbols('#####') // '98441'
faker.helpers.replaceSymbols('?????') // 'ZYRQQ'
faker.helpers.replaceSymbols('*****') // '4Z3P7'
faker.helpers.replaceSymbols('Your pin is: #?*#?*') // '0T85L1'
Shuffle
Takes an array and randomizes it in place then returns it.
Uses the modern version of the Fisher–Yates algorithm.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | The type of the entries to shuffle. | ||
| o? | T[] | [] | The array to shuffle. |
Returns: T[]
faker.helpers.shuffle<T>(o?: T[] = []): T[]
faker.helpers.shuffle() // => []
faker.helpers.shuffle() // []
faker.helpers.shuffle(['a', 'b', 'c']) // [ 'b', 'c', 'a' ]
Slugify
Slugifies the given string.
For that all spaces ( ) are replaced by hyphens (-)
and most non word characters except for dots and hyphens will be removed.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| string | string | '' | The input to slugify. |
Returns: string
faker.helpers.slugify(string: string = ''): string
faker.helpers.slugify() // => ""
faker.helpers.slugify() // ''
faker.helpers.slugify("Hello world!") // 'Hello-world'
Unique Array
Takes an array of strings or function that returns a string and outputs a unique array of strings based on that source. This method does not store the unique state between invocations.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| <T> | The type of the entries. | ||
| source | () => T | readonly T[] | The strings to choose from or a function that generates a string. | |
| length | number | The number of elements to generate. |
Returns: T[]
faker.helpers.uniqueArray<T>(source: () => T | readonly T[], length: number): T[]
faker.helpers.uniqueArray() // => []
faker.helpers.uniqueArray(faker.random.word, 50)
faker.helpers.uniqueArray(faker.definitions.name.first_name, 6)
faker.helpers.uniqueArray(["Hello", "World", "Goodbye"], 2)