Forcify

Use Force Touch in any device, today.

Intro

Forcify is a JavaScript library help you polyfill 3D/Force Touch in any device. All you need is just deal with the e.force value, dead simple:

var ele = document.querySelector('#force')

new Forcify(ele).on('force', (e) => {
    doSomething(e.force)
})

Waaaaait! Can 3D/Force Touch, a hardware feature, be really polyfilled? No, but we can emulate it with Long Press!
Forcify can help you start supporting Force Touch feature to your app or site without hesitate.

Check out demo in any unsupported device →

Download Forcify.min.js (2.4kb not gzipped)

How Forcify Works?

Forcify use a Dynamic Feature Detection to detect whether the 3D/Force Touch is really supported: If true, all hack stops, forcify just wrap the difference between OSX Force Touch and iOS 3D Touch, make things easier.
If Forcify detect that Current Browser Behave Badly (not truly support but give a !== 0 force value), Forcify would help you shim these weird browser, you would not get a wrong force value to mis-trigger your handlers.
Finally, Forcify emulate a fake force event with LONG PRESS in any unsupported device as the fallback, to keep pushing events with a growing force value after long press triggered, which help your shortcut actions designed for Force Touch can be used in any other device.

Also, Forcify provide many options such as FALLBACK_TO_LONGPRESS, LONG_PRESS_DELAY, LONG_PRESS_DURATION and SHIM_WEIRD_BROWSER to let you customize it as you need, more on Document.

Why Forcify?

3D/Force Touch release new webkitForce (Force Touch) and force (3D Touch) property to mouse and touch events. But, different browsers implement them in really different and weird way, let's have a quick glance:

Desktop:

Browser	support	`force`	`webkitForce`	`events`
OSX Safari	Force Touch	null	0 ~ 1 by Force	webkitmouseforce
OSX Safari	null	null	0	mouse
Chrome	null	null	null	mouse
Chrome Touchable-PC	null	0	null	touch

Mobile:

Browser	support	`force`	`webkitForce`	`events`
iPhone Safari	3D Touch	0 ~ 1 by Force	null	touch
iPhone Safari	null	0	null	touch
Chrome Mobile	null	1	1	touch
Chrome Mobile Nexus5	null	0 ~ 1 by touch area!	same	touch
Chrome Emulator	null	1	null	touch
Android Browser	null	null	null	touch

As you see, even just supporting the real OSX Force Touch and iOS 3D Touch you need write twice, and it is not that easy as you thought:

In OSX Safari we have awesome webkitmouseforcewillbegin and webkitmouseforcechange to get value every time changed directly.
in iOS Safari we have old touchdown, touchmove, touchup only. We has to use polling to repeat poll the force value during the entire touch duration.

Things gonna worse when you look at Chrome. Chrome on all device nowadays haven't any Force Touch support, but It provide a tricky !== 0 force value in many platform!

In Chrome Mobile, we got force=1 and webkitForce=1, which means your "Force Actions" would be ALWAYS triggered just by a click

In Chrome on Nexus5, unbelievable magic happen!, the force value is given by the area your finger touch to the screen! This bad trick really make engineer awkwardly

That is why Forcify comes to help.

Document

Check out example/ to get a detailed example

Install

The simplest way to use Forcify is adding it to your HTML page with <script>:

<script src="https://unpkg.com/forcify/dist/forcify.min.js"></script>

And you can also include Forcify in your JavaScript bundle with ES6, CommonJS or AMD syntax.

$ npm install forcify --save

Usage

Create a new Forcify instance, and use on to listen force event:

var ele  = document.querySelector('#force')
var $ele = new Forcify(ele)

// add event listener
$ele.on('force', (e) => {
    doSomething(e.force)
})

You can pass options into the Forcify constructor to override default options:

// only emit event in real supported device.
var $noFallback = new Forcify(ele, {
    FALLBACK_TO_LONGPRESS: false
})

// I am sure there would be a mess watting for u
var $noShim = new Forcify(ele, {
	SHIM_WEIRD_BROWSWR: false
})

// not easy to trigger...
var $longLongPress = new Forcify(ele, {
	LONG_PRESS_DELAY: 10000 	//ms
})

Also, you can use Forcify.config to override default options globally

// let's make duration of the force grow slower.
Forcify.config({
	LONG_PRESS_DURATION: 500
})

API

Forcify.defaults

Default options for Forcify instance.

`LONG_PRESS_DELAY: 200`

Type: Number
Default 200(ms)
Delay to trigger fake Force Touch

`LONG_PRESS_DURATION: 100`

Type: Number
Default 1000(ms)
Duration from MIN to MAX of the fake Force Touch

`FALLBACK_TO_LONGPRESS: true`

Type: Boolean
Default true
if Forcify fallback to long press on unsupport devices. if set false, Forcify will not fallback 'force' to 'long press'

`SHIM_WEIRD_BROWSER: true`

Type: Boolean
Default true
Some browser, such as Chrome, provide a very weird force value. if set false, Forcify would not try to find and ignore those weird behavior. Which means your "Force Actions" may
- be triggered just by a click in some 'force: 1' devices.
- be influenced in device like Nexus5 to give a force in (0,1)

Forcify.detection

Object save the results of dynamic detection. All fields is Boolean type and default false.

`TOUCH3D`

Unfortunately there is not a feature detection for 3DTouch so far, so Forcify use a dynamic detection to detect it.
If Forcify detects that force is support, all hacking stop.

`OSXFORCE`

OSX support real webkit force touch

`WEIRD_CHROME`

Chrome Mobile give any touchevent a 'force' property with value: 1.
Forcify has to hack it.
Forcify not detect Weird Chrome by UA but behaviors.

Known Issues

When user use a old Macbook without force touch but a Magic Trackpad 2 and switch between them.

Thanks

Special thank to:

This nice post about iOS9 inspired me to create Forcify.
3D Touch Demo by @freinbichler, which I used in my examples.

Kryndex/forcify