bakkot

Keybase proof

I hereby claim:

• I am bakkot on github.
• I am bakkot (https://keybase.io/bakkot) on keybase.
• I have a public key whose fingerprint is FD44 B8F2 65AC E177 48C5 23C8 A07A 119B 504C 8D8F

To claim this, I am signing this object:

bakkot

let frame = document.body.appendChild(document.createElement('iframe'));
frame.addEventListener('load', ()=>{
  let w = frame.contentWindow;
  
  let evt;
  w.addEventListener('error', e=>{evt = e;});
  
  let scr = w.document.createElement('script');
  scr.text = 'throw 42;';
  

bakkot

var p = () => console.log(f);
{
  p(); // undefined
  console.log(f); // function f(){}

  f = 1;
  
  p(); // undefined
  console.log(f); // 1
  

bakkot

1. d28ebe6d Normative: Specify Date.UTC when called with fewer than two arguments (#642)

2. 0916d813 Normative: Use explicit comparison to compare two lists in Valid Chosen Reads

3. 90ed6ce2 Normative: Call NumberToRawBytes instead of the conversion operation to get the byte values list in Atomics.compareExchange

4. 7949fae4 Normative: Only check for undefined count parameter in Atomics.wake, because it's not marked as optional

5. a4d0e490 Normative: Unconditionally call ToNumber on the timeout parameter in Atomics.wait, because it's not marked as optional

bakkot

globalThis

• PRO: almost shipping in Chrome, maybe used elsewhere
• PRO: is actually correct
• CON: might confuse JS beginners

Global

• PRO: maybe less likely to confuse beginners
• PRO/CON: looks like a namespace
• CON: requires even more churn on this proposal

bakkot

Optionally async functions

Or: two-color functions.

The problem: async is infectious.

There's a famous essay about this, called What Color is your Function, which I recommend reading.

For example, say you're writing a bundler. It needs to fetch resources, but is agnostic to how those resources are fetched, so it takes a readResource function from its caller. In some contexts the caller might have those resources synchronously available; in others not. That is, caller might have a synchronous readResource which returns a resource immediately, or an async readResources which returns a promise for a resource, which will need to be unwrapped with await.

bakkot

'use strict';

let { parseArgs } = require('util');

let mainOptions = { help: { type: 'boolean', short: 'h' } };
let subCommands = {
  __proto__: null,
  foo: fooCommand,
  bar: barCommand,
};

bakkot

(function x(){"use strict"; x = 1;}()); // TypeError
(function x(){x = 1; return x !== 1;}()); // write fails silently; function returns true

(function x(){"use strict"; x = (function(){throw 0;})();})() // Error 0

// These three lines rely on ES6. 
(function x(){const x = 1;})() // No-op. In particular, not a redeclaration of x.
(function (){"use strict"; const x = 1; x = 2;})() // TypeError
(function (){const x = 1; x = 2;})() // TypeError. contrast (function x(){x = 2;}());

bakkot

import fs from 'fs';
import { inspect } from 'util';
import path from 'path';
import { fileURLToPath } from 'url';

let __dirname = path.dirname(fileURLToPath(import.meta.url));

let usersToUpgrade = ['@justingrant:matrix.org'];
let targetPowerLevel = 50;
let roomId = '!nSLHQtIRJQxUJbEuGt:matrix.org'; // editor channel; this ID can be obtained from room settings -> Advanced