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Maintenance round: drop legacy features & runtime environments #98

Closed vweevers closed 3 years ago

vweevers commented 3 years ago

Across the board, drop legacy range options (https://github.com/Level/community/issues/86), node 6, node 8, IE11, stock Android browser, Safari 9-11. Use latest buffer, standard, sinon and nyc. Require support of Promise, queue-microtask, const, let, Object.assign, arrow functions and async generators.

Tasks:

vweevers commented 3 years ago

@ralphtheninja @juliangruber I tested and looked up some more ES6+ features. We can now use many goodies: Symbol, destructuring, rest parameters, block scoped let/const, Map, Set, String.prototype.startsWith, Array.from(), etc.

If we drop support of Safari < 11.1 (2018-04-12, 0.43% global share) and Safari iOS < 11.3 (2018-03-29, 0.69%) then we can also use Rest/Spread Properties and Spread in object literals. That alone is not worth it, but...

If we drop support of Safari < 12 (2018-09-17, 0.5%) and Safari iOS < 12 (2018-09-17, 0.78%) then we can use async generators with for await...of ✨. See https://github.com/Level/abstract-leveldown/pull/338 for an example. I previously planned to only support that on node.

React with thumbs up to drop those versions. I'm for.

Tests (click to expand) ```js // Temporary test for browsers test('language features', function (t) { // Destructuring const { foo } = { foo: 1 } t.is(foo, 1) // Rest/Spread Properties. Not on Safari < 11.1 (2018-04-12, 0.43%), Safari iOS < 11.3 (2018-03-29, 0.69%) // https://github.com/tc39/proposal-object-rest-spread const { a, ...rest } = { a: 1, b: 2, c: 3 } t.is(a, 1) t.same(Object.keys(rest), ['b', 'c']) // Spread in object literals // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax#spread_in_object_literals t.same({ ...rest, c: 100 }, { b: 2, c: 100 }) // Not on Safari iOS < 11.3 (2018-03-29, 0.69%) // Rest parameters ;((...rest) => t.same(rest, [1, 2, 3]))(1, 2, 3) // Block scope const x = 9 for (const x of [10]) t.is(x, 10) { const x = 11; t.is(x, 11) } t.is(x, 9) t.is(`foo ${88}`, 'foo 88') // Random stuff class Test {} t.is(typeof Test, 'function') t.is(typeof global.Map, 'function', 'map') t.is(typeof global.Set, 'function', 'set') t.is(typeof String.prototype.startsWith, 'function', 'String#startsWith') t.is(typeof String.prototype.includes, 'function', 'String#includes') t.is(typeof Array.from, 'function', 'Array.from()') t.is(typeof Number.isInteger, 'function', 'Number.isInteger') // Symbol const kA = Symbol('a') const kB = Symbol('b') const obj = { [kA]: true, [kB]: false } t.is(obj[kA], true) t.is(obj[kB], false) t.is(typeof Symbol.for, 'function', 'global symbol registry') new Promise((resolve) => resolve(123)).then((res) => { t.is(res, 123) t.end() }) }) // Not on Safari < 12 (0.5%, 2018-09-17) and Safari iOS < 12 (0.78%, 2018-09-17) test('async generator', async function (t) { let ended = false async function * generator () { try { yield 1 yield 2 yield 3 } finally { ended = true } } const res = [] for await (const x of generator()) { res.push(x) } t.same(res, [1, 2, 3]) t.is(ended, true) }) ```