Tuesday, April 25, 2017

mobile touch gotcha

I once made an angular firebase demo site called Fridge Magnets With Friends.
You can move magnets around on a virtual fridge. This involves a lot of dragging elements.
One day mobile drag stopped working, even tho I employed the clever jquery ui touch punch.

I spent hours switching the whole thing to use ngDraggable, because their mobile demo did work in mobile. Altho using ngDraggable required me to take out jquery (actually it didn't, but some forums said that would help make it work in mobile) - so I spent a while redoing the angular app without jquery.
Moment of truth: no luck.

Finally I hijacked the browser with a little shim code:
        $document.on('touchstart', function(e){

Because for the life of me I couldn't figure out why my elements weren't receiving the touchstart event in mobile.
This way I could see what element the e event was pointing to.
Turns out my footer CSS was very improperly done and covering the entire screen, so the event for touchstart, which has to have a stoppropogate() for other reasons in mobile only, never made it to the dragable elements.
Took out the footer and both solutions started working; however, jquery-ui + touch-punch still worked better than ngDraggable, so in the end, 4 hours of work (work that was, admittedly, kind of fun) got reduced to commenting out a couple lines of html. At least I understand mobile touch events now.

facepalms: 9.5

Wednesday, April 19, 2017

CSS property of the day: pointer-events

Do you have an absolutely positioned div that you want to show up on top of another element, but you want click and hover events (for instance) to pass through to the back element? Not such an uncommon use case!
just call our old (new, for me) friend
pointer-events: none;
And it'll pass those events right through.

facepalms: 1 (either I'm getting better at CSS or I just got lucky. According to this hilarious article, I got lucky.)

Saturday, March 11, 2017

quick note on webpack imports and es6 class inheritance

I know it's crazy that I'm only now using modern javascript class inheritance for the first time, but I've been more of a backend programmer most of my career.

I've got a new hobby project that I'm doing with modern webpack / es6 / vue.js, and I just learned something that I didn't find an obvious answer to in the googs.

Basically, I'd been creating utility files with instantiated objects saved as var whatever or let whatever and then exported at the bottom:

export default {
  obj: obj

And this was all well and good. But then when I wanted to define a class in the same file, the export default was overriding keyword "this". So the functions defined on the class referencing this were actually referencing my export default. I could use a fairly circular reference to get back to the instantiated class object, but really that whole route is silly.

The way to make this work is to define (but not instantiate) each class in its own file. The class itself is your export default in that file:

export default YourClass extends Whatever {
  constructor () {
  yourFunction () {
    this.stuff + 1

Then instantiate the class and use it in another file. Should have been obvious but well es6 takes some getting used to.