SOURCE

function throttle(fn, delay) {
    let timeout = null;

    return function() {
        const ctx = this;
        const args = arguments;
        if (timeout) return;

        fn.apply(ctx, args);
        timeout = setTimeout(() => {
            timeout = null;
        }, delay);
    }
}

function hello() {
    console.log('hello');
}

const delayedHello = throttle(hello, 1000);

setInterval(() => {
    delayedHello();
}, 50);