Watcher.js

A lightweight, robust and intuitive data validator for JavaScript, inspired by the observer pattern.
轻量级、高鲁棒性的 JavaScript 数据校验器，基于观察者模式设计。

Features

• 🎯 Auto-wrap primitive types (string/number/boolean)
• 🛡 Strict parameter validation
• 🚀 Single/multiple batch validation
• 🚨 Throw detailed errors on validation failure
• ✨ Zero dependencies

Quick Start

Install

Just copy Watcher.js to your project (zero dependencies):

import Watcher from './Watcher.js';

Basic Usage

// Create a Watcher instance
const numberWatcher = new Watcher({
  target: -10,
  fn: (value) => value > 0,
  ruleDesc: 'Value must be greater than 0'
});

// Basic validation
console.log(numberWatcher.judge()); // false

// Update value and validate again
numberWatcher.target.value = 15;
console.log(numberWatcher.judge()); // true

// Validation with error throw
try {
  numberWatcher.target.value = -5;
  numberWatcher.checkAndThrow();
} catch (error) {
  console.error(error.message); // Rule[Value must be greater than 0] not satisfied, current value: -5
}

// Batch validation
const phoneWatcher = new Watcher({
  target: '13800138000',
  fn: (v) => /^1[3-9]\d{9}$/.test(v),
  ruleDesc: 'Valid phone number'
});

const passwordWatcher = new Watcher({
  target: '123456',
  fn: (v) => v.length >= 6,
  ruleDesc: 'Password length ≥ 6'
});

console.log(Watcher.batchJudge(phoneWatcher, passwordWatcher)); // true

API

Constructor

new Watcher(options)

• options.target (required): The value to watch/validate
• options.fn (required): Validation function (returns boolean)
• options.ruleDesc (optional): Description of validation rule

Methods

• judge(): Execute validation, return true/false
• checkAndThrow(): Execute validation, throw error if failed
• Watcher.batchJudge(...watchers) (static): Batch validate multiple Watcher instances