TIL

Git Undos (2025-02-24)

https://retcon.app/

Undo: Deleted a commit

Run git reflog to display the list of recent head commits.
Copy the first one's hash.
Run git reset, then git stash to set changes aside.
Run git reset --hard COPIED_HASH to revert to the previous head commit.
Run git stash pop to restore stashed changes.

Undo: Rebased a branch (reword, move, delete, fixup)

See above.

Undo: Pushed to a remote

Find the output of the git push command to undo.
On the last line of the output, copy the first commit hash.
Run git push force COPIED_HASH.
If the remote branch was changed since your push, the new changes will silently be overwritten.

Undo: Deleted a branch

Find the output of the git branch -d command to undo.
Copy the commit hash.
Run git branch BRANCH_NAME COPIED_HASH.

Undo: Staged a file

To unstage the whole file, run git restore --staged FILE_PATH.
To unstage specific hunks, instead run git reset -p FILE_PATH, and manually select the hunks.

Undo: Unstaged a file

To stage the whole file, run git add FILE_PATH.
To stage specific hunks, instead run git add -p FILE_PATH, and manually select the hunks.
If some of the staged changes were not in the working directory, they cannot be recovered.

Undo: Confirmed a conflict resolution

Abort the current rebase by running git rebase --abort.
Restart the rebase from scratch. Recreate the same rebase list, perform the same message edits, and redo every conflict resolution yourself.

Zoom (2025-02-13)

You can share multiple windows, which will hide switches and other windows but allow multiple apps!

Excel (2025-01-14)

You can reference the same cell in every sheet with =SUM('*'!A1). It will probably expand to a sheet range: =SUM(Demian:Susan!A1).

cosmopolitan (2024-12-08)

fat binaries, including redbean and greenbean : greenbean might only provide a static page (404 for everything else)

Update: cosmopolitan libc (2025-01-12)

Compile C into a fat binary (run on any platform). https://justine.lol/cosmopolitan/index.html

GIT rebase branch (2024-08-07)


A ── B ── C  (<- dev)
	      🯒🯓
	        🯒── D ── E  (<- branch)

git rebase dev {branch} --onto origin/{base}


A ── B ── C  (<- dev)
      🯒🯓
	    🯒── D ── E  (<- branch)

HTML/CSS/JS Playground (2024-07-29)

MDN Playground

CSS Transparent Variable Colors (2024-07-29)

color: color-mix(in srgb, var(--color) 50%, transparent);

Statistics (2024-06-27)

Odds : % = chance of happening : F = factor to multiply by (840) : D = GCD(%, F) : = ((% x F) / D) out of (F / D)

Chance of Happening X times : N = X out of N : % = chance of happening : Ways = Combinations(N, K) : = Ways x POW(%, X) x POW(1-%, N-X)

Combinations : K out of N : = N! / (K! x (N-K)!) : shuffles are considered the same : divide Permuations by number of shuffles

Permutations : K out of N : = N! / (N-K)! : shuffles are considered different

Linux: deleting large folders

Using rsync is 3x faster than rm.


mkdir empty

rsync -aP --delete empty/ target/

HTML: `` vs ``

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/em#i_vs._em

 is for emphasis: He did WHAT??
 is for titles and other uses that don't denote emphasis: We watched Good Omens last night.

7z update option

https://7-zip.opensource.jp/chm/cmdline/switches/update.htm

7z u {archive} {paths}

Will : keep unmatched (wildcards, exclusions) : keep deleted : add new : update newer : ignore older : update same : no anti-items

7z excluding folders

& '....\Program Files\7-Zip\7z.exe' a .\Desktop\Documents.20230612.7z .\Documents\git\ .\Documents\GitHub\ .\Documents\htdocs\ .\Documents\VILLANOVA\ -xr!node_modules -xr!.git -xr!fonts

Javascript: Variable Keys in Maps

let x = "apple";

return { [x]: 10 }; // { "apple": 10 }

return { ...state, [x]: 10 };

return { ...state, apples: { [fav]: 10 } };

Python: venv

2023-04-28

Using Python's built in virtual environment means that all libraries are installed locally, allowing you to edit the libraries if understanding or functionality escapes you.


python -m venv ./.venv     ## Creates a virtual env in the current folder

source .venv/bin/activate  ## Activates the venv

PHP multi-thread

One


// returns the PID of the child to the parent

// the child will receive a 0

$isChildProcess = pcntl_fork() === 0;

if ($isChildProcess) {
    doAsyncTask();

}

Many


// A pool of threads

foreach ($urls as $index => $page) {
    if (pcntl_fork() === 0) {
        doAsyncTask();
        break; // no grandchildren!
    }

}

Bash Inputs

From Files


$var = (cat file.txt)

Prompts


echo -n "username: "

read -r user

echo -n -s "password: "

read -r pwd

SQL: Ordered List of Values

2021-04-20

You can quickly get an ordered list of ids or values by joining to a temporary table.


SELECT f.id, dbo.professors.* FROM dbo.professors

JOIN (VALUES (33),(33),(33),(90),(90)) as f(id)

ON f.id = dbo.professors.professor_id;


id  professor_id name

33  33           Sir Isaac Newton

33  33           Sir Isaac Newton

33  33           Sir Isaac Newton

90  90           Carl Sagan

90  90           Carl Sagan

Javascript: Forward Declaration

2019-08-20

Many linters check for functions to exist before they're referenced. With circular calling, you need to declare a function before it's defined. TIL this is called forward declaration.

let bind = function bindForward() {};

function ajax(url) {
	load(url).then(bind);
}

bind = function bind() {
	$("a").click(ajax);
};

Javascript: Destructuring

2019-08-08

When destructuring, JS only assigns the deepest nested keys:

const req = { query: { person: { first: "Chris", last: "Hallberg" } } };

const {
	query: {
		person: { first, last },
	},
} = req;

console.log(query); // undefined

console.log(person); // undefined

console.log(first); // "Chris"

console.log(last); // "Hallberg"

You can also assign names that don't match the keys you're grabbing. Just be careful with your brackets.

const req = { query: { data: "apples" } };

var { query: data } = req; // rename query to data

console.log(data); // { data: "apples" }

var {
	query: { data },
} = req; // destruct data from query

console.log(data); // apples

Warning: In browsers, name seems to be assigned to "[object Object]" somewhere along the line, so be careful.

Javascript: Destructuring as parameters

2019-09-19

I learned today that you can destructure variables as part of a function declaration or as part of a for-of loop:

function getHeight({ height }) {
	return height;
}

getHeight({ width: 10, height: 200, depth: 7 }); // 200

const points = [
	{ x: 3, y: 4 },
	{ x: 5, y: 5 },
];

for (let { x, y } of points) {
	console.log(`distSq = ${(x ** 2, y ** 2)}`);
}

// distSq = 25

// distSq = 50

Javascript: Destructuring as default parameters

2019-09-24

It's been a good month for destructuring. Building on the previous revelation, you can set parameter defaults with destructuring.

function showConfig({ tabSize = 2, theme = "Nord" } = {}) {
	console.log(`Theme: ${theme}, Tab Size: ${tabSize}`);
}

showConfig({ tabSize: 4, theme: "Monokai" }); // Theme: Monokai, Tab Size: 4

showConfig({ theme: "Monokai" }); // Theme: Monokai, Tab Size: 2

showConfig(); // Theme: Nord, Tab Size: 2

WebVR

Oculus Quest Debugging

A-Frame

2019-09-07

I couldn't find any official way to get debugging info from the Oculus Quest since it only connects over Wi-Fi (if at all) and the SteamVR logs don't pick up anything.

So I dropped a text element into the world and used that as my string log. You can put this element inside the camera if you want it to be visible as a UI element, but I didn't do that.


<a-text id="log" value="Hello!" color="#000" align="center" position="0 2 -5"></a-text>

const logEl = document.getElementById("log");

function log(msg) {
	logEl.setAttribute("value", msg);
}

// For updating messages

function debug() {
	requestAnimationFrame(debug);
	log(blueGun.object3D.matrix.toArray().join(","));
}

requestAnimationFrame(debug);

// For everything else

try {
	// do a backflip
} catch (e) {
	log(e);
}

Move the World, Not the Camera

A-Frame

2019-09-07

I have a few game concepts that involve pulling the player along or changing their view but trying to override the default WebVR camera is a pain.

If you do manage to get control of the camera (either with groups or with rigs) you need to then manually ensure you draw both eye "cameras" anyway. It's just more work that it's worth when you can move the whole world instead!

A heirachy like this makes this quite easy to do:

- scene
  - camera
  - world
    - hand controllers
    - all physical items

Thank you, Stefan Judis for the idea and encouragement.

TIL

HTML: <em> vs <i>

HTML: `<em>` vs `<i>`