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Isomorphic validation javascript library ISOMORPHIC-VALIDATION

Validation().changed() method

Adds state callbacks which will be invoked every time the state of the Validation changes from “valid” to “invalid” and backwards. For a “grouping” Validation, since its state depends on the grouped (nested) Validation objects, these callbacks will run even without invoking the Validation().validate() method on it directly.

Syntax

Validation().changed(callback1, callback2, /* ..., */ callbackN)

Parameters

  • callback1, ..., callbackN
    Functions to add. The callback functions will be called with the following arguments:

Return value

The Validation object.

Exceptions

If anything other than a function is passed in the corresponding error will be thrown.

Description

Adds state callbacks to the Validation object. Once the Validation in the specified state, the corresponding callbacks will be invoked one by one in the order they were added. The main purpose of state callbacks is to perform side effects related to the state. A ValidationResult object is passed into state callbacks.

Examples

import { Validation } from "isomorphic-validation";


const { log } = console;
const logFn = (fn) => (value) => (log(`${fn.name}("${value}")`), fn(value));


// predicate functions
const hasLetterA = (value) => /[Aa]+/.test(value);
const hasLetterB = (value) => /[Bb]+/.test(value);
const hasLetterC = (value) => /[Cc]+/.test(value);


// state callbacks
const startedCB = ({ isValid }) => {
    log(`\nstartedCB({ isValid: ${isValid} }) <-- before`);
};


const validCB = ({ isValid }) => {
    log(`validCB({ isValid: ${isValid} }) <-- after`);
};


const invalidCB = ({ isValid }) => {
    log(`invalidCB({ isValid: ${isValid} }) <-- after`);
};


const changedCB = ({ isValid }) => {
    log(`changedCB({ isValid: ${isValid} }) <-- changes`);
};


const validatableObject = { value: '' };


const v = Validation(validatableObject)
    .constraint( logFn(hasLetterA) )
    .constraint( logFn(hasLetterB) )
    .constraint( logFn(hasLetterC) )
    .started(startedCB)     // adding state callbacks
    .valid(validCB)         // adding state callbacks
    .invalid(invalidCB)     // adding state callbacks
    .changed(changedCB);    // adding state callbacks


validatableObject.value = 'A';
await v.validate(); // no validity state change


validatableObject.value = 'Abc';
await v.validate(); // changedCB will be called


validatableObject.value = 'ABCabc';
await v.validate(); // no validity state change


validatableObject.value = 'ABab';
await v.validate(); // changedCB will be called


// Output:
//
// startedCB({ isValid: false }) <-- before
// hasLetterA("A")
// hasLetterB("A")
// hasLetterC("A")
// invalidCB({ isValid: false }) <-- after
//
// startedCB({ isValid: false }) <-- before
// hasLetterA("Abc")
// hasLetterB("Abc")
// hasLetterC("Abc")
// changedCB({ isValid: true }) <-- changes
// validCB({ isValid: true }) <-- after
//
// startedCB({ isValid: true }) <-- before
// hasLetterA("ABCabc")
// hasLetterB("ABCabc")
// hasLetterC("ABCabc")
// validCB({ isValid: true }) <-- after
//
// startedCB({ isValid: true }) <-- before
// hasLetterA("ABab")
// hasLetterB("ABab")
// hasLetterC("ABab")
// changedCB({ isValid: false }) <-- changes
// invalidCB({ isValid: false }) <-- after