👻 Minimal library to observe nodes entering and leaving the viewport.
Be sure to also check the Intersection Observer API, a native solution which works in modern browsers, if you want to know more I wrote an introduction article explaining how it works.
# npmnpm i huntjs --save# yarnyarn add huntjs
Or include it as a script with
//unpkg.com/huntjs/dist/hunt.umd.js as source.
The package exposes an observer that receives a
Array as a first argument and an object as a second argument with the desired set of options.
;// lazy loading images using dataset and huntconst lazyImages = document;let observer = lazyImagesimagesrc = imagedatasetsrc;
Check this example working here
By default the observer will stop hunting elements when they enter and then leave the viewport.
These are the properties you can set as a configuration:
enter, function called when the element becomes visible.
leave, function method called when the element leaves completely the viewport.
Both callbacks will receive the element which triggered the action as argument.
persist, boolean and
falseby default which indicates if the targets should still be observed after they entered and left the viewport. When this option is
trueenter and leave methods will be called each time an element state changes. Recommended for constant animations triggered by scroll events.
offset, number that defines a number of pixels ahead of the element's state change,
0being the default value. Good if you want to start loading an image before the user reaches to it.
throttleInterval, number interval use for event throttling. A lower number will mean elements are detected in view quicker, but may degrade performace. A higher value will mean elements are detected in view slower, but may improve performance. The default value is
100, is recommended not to modify this.
Custom configuration over dataset
If you need exceptions over config for one or more elements,
data-hunt-persist attributes can be used. These custom values will override the ones you passed to the observer.
JSON.parse is used on these values at runtime, make sure to pass safe content.
Before commit make sure to follow conventional commits specification and check all tests pass by running