🧚memoize by closure

make a function "remember" its return values by closure.

JS ⟩ technique ⟩ memoize ⟩ by decorator

make a function "remember" its return values by using closure.

💈範例

• replit：factorial (memoization by closure)

// ⭐ factorial wrapped in a closure (IIFE)
const factorial = (() => {

    // ⭐ internal cache for f
    const cache = {};

    return function f(x) {

        // base case:
        if (x < 2) return 1;
        // recursive case:
        if (!(x in cache)) cache[x] = x * f(x - 1);

        return cache[x];
    }

})();

factorial(6)    // 720
factorial(7)    // 5040

📗 參考

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

• JS.info ⟩ Decorators and forwarding, call/apply (by decorator)
• [演算法] Fibonacci：善用 cache 和 Memoization 提升程式效能 (by parameter)
• Wictionary ⟩ memoize - to store (the result of a computation) so that it can be subsequently retrieved without repeating the computation.

👥 相關

• memoize by decorator