kentcdodds

// Feedback requested on the useDeepCompareEffect
// it just feels like a bit of work...

// HERE'S THE REASON I NEED THIS:
// when people use the useQuery hook, they'll typically
// do so like this: `useQuery(myQuery, {var1: props.value})`
// which means that passing `variables` to `useEffect` will
// trigger a rerun of the callback even if they didn't
// actually change (referrential equality)
function useQuery({query, variables}) {

dlochrie

/**
 * Combines/merges Material UI styles so that they may be used on a single
 * component with the "withStyles" HOC.
 *
 * @see {@link https://github.com/mui-org/material-ui/issues/11517#issuecomment-407509327}
 * @see {@link https://material-ui.com/customization/css-in-js/}
 *
 * Usage:
 *
 *   import { combineStyles } from '/path/to/thisFile';

bvaughn

This API was removed in React 17

---

Interaction tracing with React

React recently introduced an experimental profiler API. After discussing this API with several teams at Facebook, one common piece of feedback was that the performance information would be more useful if it could be associated with the events that caused the application to render (e.g. button click, XHR response). Tracing these events (or "interactions") would enable more powerful tooling to be built around the timing information, capable of answering questions like "What caused this really slow commit?" or "How long does it typically take for this interaction to update the DOM?".

With version 16.4.3, React added experimental support for this tracing by way of a new NPM package, scheduler. However the public API for this package is not yet finalized and will likely change with upcoming minor releases, so it should be used with caution.

gaearon

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

• Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

NWCalvank

module.exports = {
  compose,
  concat,
};

function apply(x, f) {
  return f(x);
}

function compose(...funcs) {

Chaser324

Whether you're trying to give back to the open source community or collaborating on your own projects, knowing how to properly fork and generate pull requests is essential. Unfortunately, it's quite easy to make mistakes or not know what you should do when you're initially learning the process. I know that I certainly had considerable initial trouble with it, and I found a lot of the information on GitHub and around the internet to be rather piecemeal and incomplete - part of the process described here, another there, common hangups in a different place, and so on.

In an attempt to coallate this information for myself and others, this short tutorial is what I've found to be fairly standard procedure for creating a fork, doing your work, issuing a pull request, and merging that pull request back into the original project.

Creating a Fork

Just head over to the GitHub page and click the "Fork" button. It's just that simple. Once you've done that, you can use your favorite git client to clone your repo or j

adamjohnson

"Help, I keep getting a 'Permission Denied (publickey)' error when I push!"

This means, on your local machine, you haven't made any SSH keys. Not to worry. Here's how to fix:

1. Open git bash (Use the Windows search. To find it, type "git bash") or the Mac Terminal. Pro Tip: You can use any *nix based command prompt (but not the default Windows Command Prompt!)
2. Type cd ~/.ssh. This will take you to the root directory for Git (Likely C:\Users\[YOUR-USER-NAME]\.ssh\ on Windows)
3. Within the .ssh folder, there should be these two files: id_rsa and id_rsa.pub. These are the files that tell your computer how to communicate with GitHub, BitBucket, or any other Git based service. Type ls to see a directory listing. If those two files don't show up, proceed to the next step. NOTE: Your SSH keys must be named id_rsa and id_rsa.pub in order for Git, GitHub, and BitBucket to recognize them by default.
4. To create the SSH keys, type ssh-keygen -t rsa -C "your_email@example.com". Th

danlefebvre

Here's the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the distance value is less than 25, orders the whole query by distance, and limits it to 20 results. To search by kilometers instead of miles, replace 3959 with 6371.


SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) ) + sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance FROM markers HAVING distance < 25 ORDER BY distance LIMIT 0 , 20;

crtr0

// set-up a connection between the client and the server
var socket = io.connect();

// let's assume that the client page, once rendered, knows what room it wants to join
var room = "abc123";

socket.on('connect', function() {
   // Connected, let's sign-up for to receive messages for this room
   socket.emit('room', room);
});