💾saveCallHistory(f)

make a function/method save its call history (arguments).

JS ⟩ technique ⟩ decorator ⟩ 💾 saveCallHistory(f)

(decorator) make a function/method save its "call history" (arguments).

💾 程式

• replit：saveCallHistory(f)

// 📁 saveCallHistory.js
const {log} = console;

// throttle decorator
function saveCallHistory(f){

    // ⭐️ save call history (arguments) here
    let history = [];

    // 🔸 wrapper.history (getter)
    Object.defineProperty(wrapper, 'history', {
        get() { return history }
    })

    return wrapper;

    // ⭐️ decorated function
    function wrapper(...args){
        history.push(args);        // save arguments first
        return f.apply(this, args);
    }
    
}

// export
module.exports = { saveCallHistory }

💈範例

replit：saveCallHistory(f)

// 📁 index.js
const { saveCallHistory } = require('./saveCallHistory.js');

// function
function f(...args) {
    return args.join();
}

// object
let user = {
    // method
    say(...args) { return args.join() }
};

// ⭐️ decorator: "saveCallHistory"
// ⭐️ make function/method save call history
f = saveCallHistory(f);
user.say = saveCallHistory(user.say);

// log
[
    f(1),
    f(1,2),

    f.history,           // [ [ 1 ], [ 1, 2 ] ]
    
    user.say(0),
    user.say(2, 3),
    user.say(4, 5, 6),
    
    user.say.history,    // [ [ 0 ], [ 2, 3 ], [ 4, 5, 6 ] ]

].forEach(x => console.log(x));

📗 參考

• JS.info ⟩ Decorators and forwarding, call/apply ⭐️

• YDKJS: Scope & Closures (v.2) ⟩ Ch. 6 (by IIFE, ie. closure)

• [演算法] Fibonacci：善用 cache 和 Memoization 提升程式效能 (by parameter)

• Wictionary ⟩ memoize

👥 相關

• decorator