dom-autoscroller
Big Announcement!
Version 2 of dom-autoscroller is out. You can upgrade to version 2.
Here are the differences.
- pixels option removed.
- maxSpeed option added.
- Slightly different algorithm for scrolling
- Scrolling speed changes dynamically based on distance from element edge
- Compatibility with rollup.
Scrolling in dom-autoscroller is now much smoother. So you should upgrade to version 2.
Install
npm install --save dom-autoscroller
Then use browserify, webpack, or rollup to build your script.
Or Download one of these files from the Github repo:
- dist/dom-autoscroller.js
- dist/dom-autoscroller.min.js
If you use one of these prepackaged files the global name is autoScroll.
Usage
This example uses link-css, and dragula.
require('link-css')('../node_modules/dragula/dist/dragula.min.css');
var dragula = require('dragula'),
autoScroll = require('dom-autoscroller');
var drake = dragula([document.querySelector('#list'), document.querySelector('#hlist')]);
var scroll = autoScroll([
document.querySelector('#list-container'),
document.querySelector('#container2')
],{
margin: 20,
maxSpeed: 5,
scrollWhenOutside: true,
autoScroll: function(){
return this.down && drake.dragging;
}
});
Keep In Mind
dom-autoscroller
exploits the simplicity of the single parent, to child relationship. A scrolling element with more than one children will likely not work well with dom-autoscroller
.
For clarity here is a more complete example:
<!DOCTYPE html>
<html>
<head>
<title>Drag test</title>
<style>
#list-container{
height: 100px;
overflow-y: auto;
}
</style>
</head>
<body>
<div id="list-container">
<ol id="list" type="1">
<li>zero</li>
<li>one</li>
<li>two</li>
<li>three</li>
<li>four</li>
<li>five</li>
<li>six</li>
<li>seven</li>
<li>eight</li>
<li>nine</li>
<li>ten</li>
<li>eleven</li>
<li>twelve</li>
<li>thirteen</li>
<li>fourteen</li>
<li>fifteen</li>
</ol>
</div>
<div id="container2">
<ol id="hlist">
<li>zero</li>
<li>one</li>
<li>two</li>
<li>three</li>
<li>four</li>
<li>five</li>
<li>six</li>
<li>seven</li>
<li>eight</li>
<li>nine</li>
<li>ten</li>
<li>11</li>
<li>12</li>
<li>13</li>
<li>14</li>
<li>15</li>
</ol>
</div>
<script>
require('link-css')('../node_modules/dragula/dist/dragula.min.css');
var dragula = require('dragula'),
papyri = require('dom-autoscroller');
var drake = dragula([document.querySelector('#list'), document.querySelector('#hlist')]);
var scroll = autoScroll([
document.querySelector('#list-container'),
document.querySelector('#container2')
],{
margin: 20,
pixels: 5,
scrollWhenOutside: false,
autoScroll: function(){
return this.down && drake.dragging;
}
});
</script>
</body>
</html>
If you look at the last example notice the containers have only one child, and that they're different from the containers used by dragula. In theory multiple children could work with dom-autoscroller
, but the children scrolling might interfere with the workings of the library dragula.
jsfiddle Demo of dom-autoscroller
Auto Scroller API
autoScroll(element|elements, options) -> instance
Create an auto scroller on an element, or and array of elements.
The element should have only one child element to work consistently.
options.margin = Integer
An inner area to detect when the pointer is close to the edge.
options.autoScroll = Function
A callback function used to determine if the element should scroll, or when the element should scroll.
Return a boolean value from this function to allow scrolling.
options.maxSpeed = Integer
maxSpeed
defaults to 4.
Speed effects in dom-autoscroller:
- Speed adjusts dynamically depending on how close to the edge your pointer is.
- Speed is pixels per frame.
maxSpeed
limits pixels per frame.
options.pixels = Integer
removed in version 2
Set how many pixels per second you want to scroll during the auto scrolling action. More is smoother.
Speed was pixels/second in version 1, and in version 2 speed is pixels/frame.
options.scrollWhenOutside = Boolean
Whther or not it should continue to scroll when the pointer is outside the container. Defaults to false.
Auto Scroller Properties
down = Boolean
Is the pointer down?
point = Object
A reference to the pointer object.
Auto Scroller Methods
autoScroll
The function you set in the constructor options for options.autoScroll
.
destroy
Remove all event listeners needed to be able track the pointer.
Undocumented methods
There are undocumented methods in version 2.
These are:
- add()
- remove()
These methods add, or remove elements from dom-autoscroller.
Why are these considered undocumented even though there here in the document? :)
add
, and remove
are incomplete, and there is no detailed explanation. Use these methods at your own risk.
About
There are tons of reasons to have auto scrolling. The main one being sometimes a finger can't reach the mouse wheel comfortably. dom-autoscroller
is a comfort module.
This is also a nice small module to do this kind of thing when auto scrolling is all you need.