form-validations v1.1.0

Form validation in 1KB

A library that makes form validation fun again. When trying out various different form validation libraries, I didn't found one where one could easily change different rules, and customize the error messages as well.

Simple example:

import { validString } from "form-validations";

const isString = validString("not a string"); // Simple helper for custom messages

isString("hello world!"); // Returns: []. No errors means field is valid
isString(1234); // Returns: ["not a string"]

A more complex example with chained validations:

import { chain, firstError, validString } from "form-validations";

const isString = validString("not a string");

// Custom validator
function isHello(value) {
  if (!/hello/g.test(value)) {
    return "value does not contain 'hello'";
  }

  return true;
};

// Collect all errors
const validate = chain(isString, isHello);

validate("hello world!"); // Returns: []. No errors means field is valid
validate(1234); // Returns: ["not a string", "value does not contain 'hello'"]

// Stop on first error
const validate = firstError(isString, isHello);
validate(1234); // Returns: ["not a string"]

This library was built to allow easy chaining of validations.

API

chain(...validators): string[]

Easily chain validators together. Each validator can push an error message to the resulting array.

firstError(...validators): string[]

Contrary to chain this function will stop at the first validator that returns an error. The resulting string array will always have a length of 1.

Available validations

Each validation function must return either true or an error message of type string.

Available normalizers

Often you need to normalize data when dealing with form elements.

import { normalizeBoolean } from "form-validations";

normalizeBoolean("false"); // returns false;
normalizeBoolean(1); // returns true;
normalizeBoolean([]); // returns false;

LICENSE

MIT, see LICENSE.md