Revisit our browserslist config

[XhmikosR]

Closes #29314.

I kept the Edge patch separate because ATM the update hasn't shipped on all supported Windows versions: https://support.microsoft.com/en-us/help/4541302/the-new-microsoft-edge-is-available (see also my last point)

master branch:

Browsers:
  Chrome for Android: 81
  Firefox for Android: 68
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  Edge: 83, 81, 80, 79, 18, 17
  Firefox: 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 13.4, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 46
  Opera: 68
  Safari: 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 11.1

These browsers account for 92.74% of all users globally

This branch:

Browsers:
  Chrome for Android: 81
  Firefox for Android: 68
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  Edge: 83, 81
  Firefox: 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 13.4, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 46
  Opera: 68, 67
  Safari: 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 11.1, 10.1

These browsers account for 91.88% of all users globally

This branch without the Edge patch:

C:\Users\xmr\Desktop\bootstrap>npx autoprefixer --info
Browsers:
  Chrome for Android: 81
  Firefox for Android: 68
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  Edge: 83, 81, 80, 79, 18, 17
  Firefox: 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 13.4, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 46
  Opera: 68, 67
  Safari: 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 11.1, 10.1

These browsers account for 93.97% of all users globally

Notes:

1. Do note that dropping Opera Mini does not gain us anything, i.e. no prefix is removed/added.
2. We could drop the defaults change, but IMO we should change what we were using because 1 last version isn't proper
3. I'd also argue about the Edge change, but I don't want to hold us back in v5 either. That being said, it does feel too soon to drop it, but depends to when we will actually ship v5.0.0 stable.

Preview: https://deploy-preview-30986--twbs-bootstrap.netlify.app/

EDIT: actually dropping Opera Mini should allow us to use const/let. I will experiment with that later.

[mdo]

Hmm, makes me think we could drop legacy Edge (17 and 18) given the difference there in those %s.

[mdo]

Is this okay to review and get merged @XhmikosR?

[XhmikosR]

I'm still not sure if it's the right time to drop Legacy Edge. The percentage, which might seem small, does not reflect the real number. I'm just thinking out loud here so that we make the right choice for our users and the project.

Also, I wanted to make another change, I'll do it later.

[ffoodd]

Despite the fact that I'd love to use logical properties for RTL, I'm not sure about dropping Legacy Edge.

The New Edge is only available for every Windows for a few weeks, isn't it?

[XhmikosR]

Yeah, it hasn't shipped to all supported Windows 10 versions yet AFAICT and I don't know where they track this.

Also, there might be more stuff we can remove if we go with the Edge removal and ideally I'd like all the related changes to be in the same PR (not this one).

EDIT: Also, do note that the Legacy Edge removal saves us a significant amount of bytes from the JS dist files. CSS doesn't save a lot.
EDIT2: It's because the arrow functions and other ES6+ features are no longer transpiled because they are supported by the target browserslist config.

So, I'm not sure how to proceed.

[mdo]

Chatted with @XhmikosR about this in Slack and wanted to reiterate here. I'm in favor of dropping this knowing that it'll be a couple months to stable v5 and we're going to be working on this for at least a year, hopefully a little more. Having some foresight into what things will look like at that point is what I'm hoping to rally around. if that makes sense.

[mdo]

Also slating this for alpha 2 now to make sure we're all aligned on it :).

[XhmikosR]

So, here's the current situation:

• use browserslist defaults which is > 0.2%, last 2 versions, Firefox ESR, not dead
• remove Android since Android WebView is Chromium based
• drop Legacy Edge support; Microsoft will ship the new version to Windows >= 1803

C:\Users\xmr\Desktop\bootstrap>npx autoprefixer --info
Browsers:
  Chrome for Android: 84
  Firefox for Android: 79
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 85, 84, 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 49
  Edge: 84, 83
  Firefox: 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 13.4-13.5, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2, 9.3
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 46
  Opera: 70, 69
  Safari: 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 12.0, 11.1-11.2

These browsers account for 93.64% of all users globally

The only "issue" I see is iOS 9.3 being included, and some other browsers we might not care about.

I think if we switch to >= 0.25% and last 3 major versions it might be better?

Browsers:
  Chrome for Android: 84
  Firefox for Android: 79
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 85, 84, 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 49
  Edge: 84, 83, 81
  Firefox: 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 13.4-13.5, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 46
  Opera: 70, 69, 68
  Safari: 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 12.0, 11.1-11.2, 10.1

These browsers account for 93.72% of all users globally

/CC @twbs/team

[XhmikosR]

Also, do note that with this patch as is the generated JS files use const/let and ES6+. Not sure if that's OK for the consumers of the dist files.

EDIT: scratch that, it was due to another local change I had (>= 0.25% and last 3 major versions)

[mdo]

Let's roll with the second option I think @XhmikosR. We can drop iOS 9.3 IMO.

[XhmikosR]

I need to revisit this thoroughly because 1) iOS 10 tests fail and 2) I see const/let and more ES6 features in our dist files.

[mdo]

Pre-approving for when this comes up for review.

[XhmikosR]

C:\Users\xmr\Desktop\bootstrap>npx autoprefixer --info
Browsers:
  Chrome for Android: 86
  Firefox for Android: 82
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 86, 85, 84, 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  Edge: 86
  Firefox: 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 14, 13.4-13.7, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 59
  Opera: 72
  Safari: 14, 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 12.0

These browsers account for 92.57% of all users globally

C:\Users\xmr\Desktop\bootstrap>npx autoprefixer --info
Browsers:
  Chrome for Android: 86
  Firefox for Android: 82
  And_qq: 10.4
  UC for Android: 12.12
  Android: 81
  Baidu: 7.12
  Chrome: 86, 85, 84, 83, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  Edge: 86, 85
  Firefox: 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60
  iOS: 14, 13.4-13.7, 13.3, 13.2, 13.0-13.1, 12.2-12.4, 12.0-12.1, 11.3-11.4, 11.0-11.2, 10.3, 10.0-10.2
  Kaios: 2.5
  Opera Mini: all
  Opera Mobile: 59
  Opera: 72, 71
  Safari: 14, 13.1, 13, 12.1, 12, 11.1, 11, 10.1, 10
  Samsung: 12.0, 11.1-11.2

These browsers account for 94.65% of all users globally

Let's land this as is; it doesn't really change anything in the dist files as is. Due to the issue we are having when removing Android, I say we revisit this later.