virtual-scroll-handler
v1.12.2
Published
Virtual scrollbar, for when you need to handle scroll events without an actual DOM scrolling.
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virtual-scroll-handler
Allows you to handle scroll events in order to trigger and control animations, without having to deal with an actual DOM scrolling. This class creates a virtual scrollbar and is mobile friendly.
See it in action: https://atmos.leeroy.ca/
Install
npm i virtual-scroll-handler
Hello world
import virtualScrollHandler from 'virtual-scroll-handler'
let scroller = new virtualScrollHandler({
range: [0, 2000],
triggers: [{
y: 1000,
callback: () => {
console.log("Callback triggered");
}
}]
});
(function loop() {
requestAnimationFrame(loop);
scroller.update();
})();
Options
range[min, max]
Min and max scroll edges.
A single mouse scroll down event will approximately increment the Y position by 100, so a range from 0 to 200 implies around 2 scroll events to hit the bottom of the virtual scrollbar.
startY
Y starting position within the provided range.
Default is 0.
lerpAmount
For each iteration of the linear interpolation, the amount to interpolate between the mouse position and the camera position. A smaller value will make the animation smoother.
Default is .1
Must be set between 0 and 1.
lerpAmountSwipe
Similar to lerpAmount
but only affects swipe gestures for mobile devices.
Default is lerpAmount * 4.
mobileSensibility
Controls the strength of a swipe on mobile devices.
Default is 1.
scrollbar
An object of options.
If set to false
, the default scrollbar creation will be disabled.
Else, will add a scrollbar in the DOM, before the closing </body>
tag.
scrollbar.position
Defines the position of the scrollbar in the window.
Possible values are 'top', 'bottom', 'left' and 'right'.
Default is right
.
scrollbar.width
Default is 6
.
scrollbar.distanceFromEdge
Distance between the scrollbar and the edge of the viewport.
Default is 0
.
scrollbar.customStyles
String.
Only active if createScrollbar
is set to true.
Adds custom css styles to the DOM.
Note: Instances of virtual-scroll-handler are indexed with unique IDs starting from 0. This ID is referenced in the name of DOM classes and ids.
Example:
const scrollHandler = new virtualScrollHandler({
range: [0, 1000],
scrollbar: {
customStyles: `.vsh-scrollbar-0 { /* <- this is the first instance, so the id is 0 */
...
}`
}
});
fadeOutDelay
Time in ms after which the scrollbar will fadeout once it has stopped moving. Default is false.
handleSize
Size of the scroll bar handle in percent of the viewport height. Default is .1, since by default, the handle take 10% of the viewport height.
triggers
Array of objects.
This is where you declare when and what is going to happen.
Each trigger is an object made of these options:
y
The Y position value which will trigger the action when reached.
condition
Default is >y
, meaning that the callback is triggered when the current virtual scroll position is above the y
trigger value.
callback
The callback function to trigger.
once
Default is false.
If set to true, the callback function will only be triggered once.
Properties
completion
Returns a number between 0 and 1.
let scroller = new scrollHandler({
range: [0, 2000]
});
console.log(scroller.completion);
deltaY
The difference between the current Y position and the previous one.
active
Default is true.
If set to false, the scroll is disabled.
domElements
An object containing:
.scrollbar: the DOM element of the whole scrollbar and its children
.handle: the part of the scrollbar that moves vertically
scroller.domElements.scrollbar.style.opacity = 0;
Methods
goTo( distance: number, animated: bool)
Scroll to a point in the range of the scroller.
The 'animated' parameter makes the scroll instant or animated. Default is true.
scroller.goTo( 500, false );
setHandleSize( size: number)
Sets the size of the scrollbar handle as a percentage.
scroller.setHandleSize( .2 ); // The handle will take up 20% of the scrollbar
Example
import scrollHandler from 'virtual-scroll-handler'
new scrollHandler({
range: [0, 2000],
startY: 0,
triggers: [{
y: 1000,
condition: '<y',
callback: () => {
console.log("Callback triggered");
},
once: true
}],
createScrollbar: true,
customScrollbarStyles: `.vsh-scrollbar { mix-blend-mode: difference; }`,
fadeOutDelay: 500
});
(function loop() {
requestAnimationFrame(loop);
scroller.update();
console.log(scroller.completion);
})();