WeChat Calculator Bot

Background

I’ve been following WeChat bots for quite some time. As a frontend developer with solid Node.js knowledge, I wanted to create my own WeChat calculator bot. The reason is simple: every time I need a calculator, it’s very inconvenient. The calculator app on my phone is buried deep in folders, hard to find, and putting it on the home screen feels like a waste of space. So I thought of using Wechaty to implement a personal WeChat calculator bot that can perform basic arithmetic operations like addition, subtraction, multiplication, and division.

Features

Addition, subtraction, multiplication, and division

Implementation Logic

The logic is quite simple: use Wechaty to receive user messages, filter the messages, and when a user inputs something like “1+1”, directly evaluate the expression and return the result to the user.

Dependencies

• wechaty: Core Wechaty library
• wechaty-puppet-padplus: iPad protocol implementation for Wechaty

Implementation Process

function calculator(intxt, callback) {
  return new Promise(function (resolve, reject) {
    var a = intxt;
    try {
      intxt = intxt.replace(/=|等|等于|\?/, '');
      intxt = intxt.replace(/加/g, '+').replace(/减/g, '-').replace(/乘/g, '*').replace(/除/g, '/');
      a = eval(intxt);
    } catch(e){
      // console.log('========error', e);
    }
      resolve(a);
    });
}

async function onMessage (msg) {
  const contact = msg.from()
  let text = msg.text()
  const room = msg.room();

  if (room) return;
  if(msg.self()){ // Skip self messages
    return;
  }
  if (text) {
    text = text.replace(/[。，、,.]$/gi, '').replace(/\s*/gi, "");
  }
  if (msg.type() === bot.Message.Type.Text && /^\d+.{1}\d+/gi.test(text)) { // Text messages
    let result = await CalcFunc.calculator(text);
    await msg.say(result+'');
  }
}

Local Setup

1. Clone the project

git clone https://github.com/leiroc/wechat-calculator.git
cd wechat-calculator

1. Install dependencies

npm install

1. Start the project

node app.js

Demo

Acknowledgments

Thanks to the Wechaty team for providing the WeChat bot SDK, allowing developers to focus on business logic. Thanks to Juzi.BOT for providing the Pad protocol token. I saw many DLL-based implementations but decided not to explore them due to time constraints.

Author: Ray (雷) Code: Github

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中文版: 微信计算器机器人