memoize.js

/*
 Simple Memoization example used Closure
 Made by: Muhammad Lahin
*/

const myObj = {memo: {}}
const memo = fn => {
    return (first_name, last_name) => {
        let slice = Array.prototype.slice;
        let key = JSON.stringify(slice.call(arguments));
        if(!myObj.memo[key]) {
            let result = {}
            result.first_name = fn(first_name);
            result.last_name = fn(last_name);
            myObj.memo[key] = result;
        }
        return myObj.memo[key];
    }
}

function firstLetterUpperCase(name) {
    return name.charAt(0).toUpperCase() + name.slice(1);
}

let _firstLetterUpperCase = memo(firstLetterUpperCase);

console.time()
console.log(_firstLetterUpperCase("lahin", "hussain"))
console.timeEnd()

console.time()
console.log(_firstLetterUpperCase("lahin", "hussain"))
console.timeEnd()