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Consider the following function:

function isContainingDirectory(path, callback) {
  const directoryName = getDirectoryName(path),
        numTotalChecks = 2;

  let numChecksDone = 0;
      callbackHasBeenCalled = false;

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Summary

The following type of callbacks:

(err, ...args) => {
  if (err) return callback(err);
  // Rest of the callback code (that is, the "happy path").
}

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const parser = require('@babel/parser');
const traverse = require('@babel/traverse');

// console.log('parser is', parser);
// console.log('traverse is', traverse);

const code = `function square(n) {
  return n * n;
}`;

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I had a very sneaky bug that I spent a fair bit of time debugging (using console.log initially). When I finally used the real debugger (node inspect my-script.js), I was able to understand where the problem was. The problem was at the following, can you detect the problem?

/**
 * - Create a shallow clone of `object`
 * - Set the prototype of the clone to the prototype of the original object object
 * - Recursively remove _own_ properties of the clone that:
 *   - Are `null` or `undefined`
 *   - Have 0 length
 *   - Have been listed in the `properties` parameter

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Summary

npm version 7 and above (also before version 3) installs peer dependencies by default, if they aren't satisfied. (From npm version 3 until 7, users had to manually install the peer dependencies. npm only showed a warning to the users about "unmet peer dependencies" in those versions, but didn't install them by itself). However, Yarn neither installs peer dependencies by default, nor shows a warning about unmet peer dependencies. Hence, when you install a package that has an unmet peer dependency, it will simply not work.

Explanation

Current version (as of 2021-01-28) of Babel's command line program can be installed with:

npm install --global @babel/cli

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Disclaimer: This article applies to Babel that runs on Node.js, which is the most common way of running Babel. I didn't check how Babel on a web browser works. The reason I wrote this article is because I didn't notice anywhere on Babel docs that explains what exactly is a Babel plugin. Babel docs mention how a Babel plugin works, what's its purpose, etc. but as far as I can tell, they don't mention what a Babel plugin is.

A Babel plugin is a CommonJS module, whose export is expected by Babel to be a function. That's it. Note that I didn't say "default export", because there is no concept of "default export" in CommonJS. In CommonJS, there is only the module.exports property. This property's value can be any valid JavaScript value. However, Babel expects the value of the module.exports property of a CommonJS module that is designated as a Babel plugin to be a JavaScript function.

How do we know that a Babel plugin is a "CommonJS module"? Can't it be an "ES6 module" as well? No. A Babel plugin is a Com

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Summary

Specify the path to your plugin script with a leading ./ or ../. A Babel plugin is a regular CommonJS module, and Babel "processes" what you provide as the "plugin identifier" before converting it to a "module identifier" and loading that CommonJS module using the require function of Node.js.

Per [Node.js module loading rules][Node.js modules API document], a module identifier the does not start with ./ or ../ is searched in node_modules/. Since a plugin that we are currently developing is (most likely) not in a node_modules/ folder, we must specify the path to it with a leading ./ or ../ so that the plugin will not try to be located in a node_modules/ folder, but it will be tried to be located in the relative path that we provide.

Details

As mentioned in ["What is a Babel Plugin?"], a Babel plugin is nothing but regular a CommonJS module, whose value of module.exports is expected to be a function by Babel. Hence, after creating a Babel plugin (i.e after creating a Comm

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Because GitHub handles them using JavaScript. Their ID's are prefixed with user-content-. Hence, an ID is like user-content-some-fragment, whereas the fragments are expressed only as some-fragment.

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git filter-repo --email-callback ' return b"new_email_address" if email == b"old_email_address" else email '

Documentation

If git-filter-repo is not installed, you have to install it. git-filter-repo is a program:

1. Developed by Elijah Newren, who is a veteran contributor to Git.
2. Endorsed by Git as the replacement for the git-filter-branch program, which had numerous issues.

For reasons that I don't know, it has to be installed separately, instead of being included in a Git distribution. At least this is the case in the version of Git that I'm using.

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Use the touch command like:

touch -t '1509260825' <path to the file>

This will set both the creation and modification date of the file to "2015-09-26 08.25".

To preserve the creation and modification dates when coping a file, use the -p option of the cp command like:

cp -p <path to the file> <destination path>