Trigger event when user scroll to specific element - with jQuery

Question

I have an h1 that is far down a page..

TRIGGER EVENT WHEN SCROLLED TO.

and I want to trigger an alert

Answer 1

Intersection Observer can be the best thing IMO, without any external library it does a really good job.

const options = {
            root: null,
            threshold: 0.25, // 0 - 1 this work as a trigger. 
            rootMargin: '150px'
        };

        const target = document.querySelector('h1#scroll-to');
        const observer = new IntersectionObserver(
           entries => { // each entry checks if the element is the view or not and if yes trigger the function accordingly
            entries.forEach(() => {
                alert('you have scrolled to the h1!')
            });
        }, options);
        observer.observe(target);