Generic

Generic are rules that you can apply besides any type

Methods

Reference

required([options])

Marks a field as required which will not allow undefined and null or empty string, object, array as value.

Optionally, you can provide a options object that can hold message and constraints.

Example :

import { Field } from "v4f";

const field = Field()
    .string()
    .required();

field.validate("str"); // true
field.validate(""); // false
field.validate(undefined); // false
field.validate(null); // false

NOTE : you can marks a field as Optional using the not modifier.

import { Field } from "v4f";

const field = Field()
    .string()
    .not.required();

field.validate("str"); // true
field.validate(""); // true
field.validate(undefined); // true
field.validate(null); // true
field.validate(9); // false, if the Field is optional and is not empty other rules are checked

custom([options])

Pass a custom validator function to check against the value of the field.

Optionally, you can provide a options object that can hold message and constraints.

NOTE : : validator function must return True or False.

Example :

import { Field } from "v4f";

const checkUppercase = value => value === value.toUpperCase();

const field = Field()
    .string()
    .custom(checkUppercase)
    .required();

field.validate("STR"); // true
field.validate("str"); // false

none([options])

Checks if the field value is a null or undefined or empty string, object, an array.

Optionally, you can provide a options object that can hold message and constraints.

Example :

import { Field } from "v4f";

const field = Field()
    .object()
    .none();

field.validate({ a: 1 }); // false
field.validate(undefined); // true
field.validate(null); // true
field.validate({}); // true
field.validate(""); // false, because the type is object not string

empty([options])

Checks if the field value is empty.

Optionally, you can provide a options object that can hold message and constraints.

Example :

import { Field } from "v4f";

const field = Field()
    .string()
    .empty();

field.validate(""); // true
field.validate(undefined); // false
field.validate(null); // false
field.validate("lss"); // false

equals(value, [options])

Checks if the field value equals to value given as an argument to the rule.

Optionally, you can provide a options object that can hold message and constraints.

NOTE : equals rule use no strict operator == for equality , see exact for strict.

Example With String:

import { Field } from "v4f";

const field = Field()
    .string()
    .equals("5")
    .required();

field.validate("5"); // true
field.validate("lss"); // false

Example With Array:

import { Field } from "v4f";

const field = Field()
    .array()
    .equals([3, 3, [2, 2]])
    .required();

field.validate([3, 3, [2, 2]]); // true
field.validate([2, 2]); // false

exact(value, [options])

Checks if the field value equals to value given as an argument to the rule.

Optionally, you can provide a options object that can hold message and constraints.

NOTE : equals rule use strict operator === for equality.

Example With String:

import { Field } from "v4f";

const field = Field()
    .string()
    .equals("5")
    .required();

field.validate("5"); // true
field.validate("lss"); // false

Example With Array:

import { Field } from "v4f";

const arr = [3, 3, [2, 2]];

const field = Field()
    .array()
    .equals(arr)
    .required();

field.validate(arr); // true
field.validate([3, 3, [2, 2]]); // false

onOf(arr, [options])

Checks if the field value equals to one of the values in the array given as argument.

Optionally, you can provide a options object that can hold message and constraints.

NOTE : onOf rule use no strict operator == for equality , see exactOneOf for strict.

Example

import { Field } from "v4f";

const field = Field()
    .number()
    .onOf([1, 3, 5, 7, 9]);

field.validate(1); // true
field.validate(7); // true
field.validate(4); // false

exactOneOf(arr, [options])

Checks if the field value exact equals to one of the values in the array given as argument.

Optionally, you can provide a options object that can hold message and constraints.

NOTE : onOf rule use strict operator === for equality .

Example

import { Field } from "v4f";

const field = Field()
    .number()
    .onOf([1, 3, 5, 7, 9]);

field.validate(1); // true
field.validate(7); // true
field.validate(4); // false
← WhenString →