Formation.js
Rules plus Values equals Results
Formation.js is a simple validation engine that exposes validate(rules: Rules, values: Values): Results function. See type definitions below.
Type Definitions
Value
export type Value = boolean | number | string | Object | null
Value is something that we might want to validate, it can be one of following types: boolean, number, string, Object or null. By convention null is used for to denote empty or default values. When input field has nothing in it, or radio button is neither selected nor deselected - it‘s empty.
Message
type Message = string
Message is a string, In real life application message should be an id pointing to i18n/l10n bundle.
Validation
type Validation = (value: Value) => ?Message
Validation is a function that accepts Value and returns Message or null (Maybe Message).
Result
type Result {value: Value, messages: Message[]}
Result structure contains value and list of messages, empty list of messages means that result is valid.
Rule
export type Rule = {validations: Validation[], defaultValue: Value, required: boolean}
Rule structure contains list of validation functions, default value if any and required flag. Rule can be executed against Value to produce Result.
Rules
type Rules = {[string]: Rule}
Rules structure is a map of keys and rules.
Values
type Values = {[string]: Value}
Values structure is a map of keys and values.
Results
type Results = {[string]: Result}
Results structure is a map of keys and results