From 5482e2cc966aa827c28a874c70d7c6c320f0638c Mon Sep 17 00:00:00 2001 From: Chris Rebert Date: Tue, 24 Nov 2015 04:29:22 -0800 Subject: [PATCH] Gruntfile: Add comments explaining CSS prefixing policy [skip sauce] --- Gruntfile.js | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/Gruntfile.js b/Gruntfile.js index 5e6dad8668..e0128d3e29 100644 --- a/Gruntfile.js +++ b/Gruntfile.js @@ -23,19 +23,33 @@ module.exports = function (grunt) { var mq4HoverShim = require('mq4-hover-shim'); var autoprefixer = require('autoprefixer')({ browsers: [ - 'Android 2.3', - 'Android >= 4', - 'Chrome >= 35', - 'Firefox >= 31', + // + // Official browser support policy: + // http://v4-alpha.getbootstrap.com/getting-started/browsers-devices/#supported-browsers + // + 'Chrome >= 35', // Exact version number here is kinda arbitrary + // Rather than using Autoprefixer's native "Firefox ESR" version specifier string, + // we deliberately hardcode the number. This is to avoid unwittingly severely breaking the previous ESR in the event that: + // (a) we happen to ship a new Bootstrap release soon after the release of a new ESR, + // such that folks haven't yet had a reasonable amount of time to upgrade; and + // (b) the new ESR has unprefixed CSS properties/values whose absence would severely break webpages + // (e.g. `box-sizing`, as opposed to `background: linear-gradient(...)`). + // Since they've been unprefixed, Autoprefixer will stop prefixing them, + // thus causing them to not work in the previous ESR (where the prefixes were required). + 'Firefox >= 31', // Current Firefox Extended Support Release (ESR) // Note: Edge versions in Autoprefixer & Can I Use refer to the EdgeHTML rendering engine version, // NOT the Edge app version shown in Edge's "About" screen. // For example, at the time of writing, Edge 20 on an up-to-date system uses EdgeHTML 12. // See also https://github.com/Fyrd/caniuse/issues/1928 'Edge >= 12', 'Explorer >= 9', + // Out of leniency, we prefix these 1 version further back than the official policy. 'iOS >= 7', - 'Opera >= 12', - 'Safari >= 7.1' + 'Safari >= 7.1', + // The following remain NOT officially supported, but we're lenient and include their prefixes to avoid severely breaking in them. + 'Android 2.3', + 'Android >= 4', + 'Opera >= 12' ] });