Remove selectionStart polyfill?

[gaearon]

Looking at this code:

react/packages/react-dom/src/client/ReactInputSelection.js

Lines 91 to 100 in bee4baf

	if ('selectionStart' in input) {
	// Modern browser with input or textarea.
	selection = {
	start: input.selectionStart,
	end: input.selectionEnd,
	};
	} else {
	// Content editable or old IE textarea.
	selection = ReactDOMSelection.getOffsets(input);
	}

When would selectionStart not exist? According to http://help.dottoro.com/ljtfkhio.php, only in IE8. (It might be wrong though.)

It would be nice to check, and remove the relevant code if it's supported everywhere else.

[gaearon]

Tagging as good first issue—the outcome is a report on which browsers support the feature.

[jquense]

I am fairly sure it's ie8 only for inputs/text areas. We just removed the equivalent code in a bunch of libraries with no (observable) issues so far. I'd imagine tho the story is different contenteditable? Maybe the draftjs folks have some insight?

[gaearon]

Tagging @flarnie

[gaearon]

(I haven’t thought about CE but you might be right!)

[Miklet]

I also checked at caniuse. Seems support starts from IE9.

[bs91]

MDN also reports IE9 and up support.

[flarnie]

The comment // Content editable or old IE textarea. is a concern because we rely on contenteditable in Draft.js. Let me look into it a bit.

[flarnie]

This example shows that unlike other inputs or a textarea, 'selectionStart' is not available on a contenteditable div. So let's keep this polyfill, and also add a test for this somewhere. I would love to have a Draft.js fixture, but maybe just a contenteditable fixture or test.
https://codepen.io/anon/pen/ZagBrx?editors=1111
I was just playing with that in latest Firefox.

[flarnie]

For anyone interested in more info:
Only input and textarea are defined as having the text field selection API.
https://www.w3.org/TR/2008/WD-html5-20080610/editing.html#textFieldSelection

In Draft we rely on the similar but different Selection interface -
https://www.w3.org/TR/2008/WD-html5-20080610/editing.html#selection1
which we wrap in an immutable record -
https://github.com/facebook/draft-js/blob/master/src/model/immutable/SelectionState.js