enter-view.js

Dependency-free JavaScript library to detect when element enters into view. See demo. It uses requestAnimationFrame in favor of scroll events for less jank. Less than 1kb minified + gzipped.

Usage

enterView({
	selector: '.class-name',
	enter: function(el) {
		el.classList.add('entered');
	}
});

enterView({
	selector: '.class-name',
	enter: function(el) {
		el.classList.add('entered');
	},
	offset: 0.5, // enter at middle of viewport
	once: true, // trigger just once
});

Options

selector: [string or array of elements] required

Takes a class, id, or array of dom elements.

enter: [function] required

Callback function that returns the element that was entered.

exit: [function] optional

Callback function that returns the element that was exited.

offset: [number] optional (defaults to 0)

A value from 0 to 1 of how far from the bottom of the viewport to offset the trigger by. 0 = top of element crosses bottom of viewport (enters screen from bottom), 1 = top of element crosses top of viewport (exits screen top).

once: [boolean] optional (defaults to false)

Whether or not to trigger the callback just once.