Cheatsheet

Cheatsheet of commands/code snippets/code examples/configurations because I keep forgetting them.

Nodejs

• Node modules binaries directory: ./node_modules/.bin
• setTimeout: setTimeout(() => console.log('timeout!'), 1000);
• Set Timeout Promise:

const util = require('util');
const setTimeoutPromise = util.promisify(setTimeout);
setTimeoutPromise(1000).then(() => doSomething());

• Handle unhandled Promises:

process.on('unhandledRejection', (err) => {
  console.error(err);
  if (module.exports.abort) {
    process.abort();
  }
  process.exit(1);
});

NPM

• Save dev flag: --save-dev
• Publish scoped public package: npm publish --access public

NVM

• Install version: nvm i <version>
• List versions: nvm ls
• Set default version: nvm alias default <version>

Gulp

• Specify Gulpfile: gulp --gulpfile <filename>
• Example gulpfile that reloads server and browser after any change: gulpfile

JavaScript

• Reduce: arr.reduce((accumulator, currentValue) => doSomething(), initialValue)
• Remove element i in array: var removed = array.splice(i,1);
• Clone an array: const cloned = [...array];
• Sort array of numbers: array.sort((n1, n2) => n1-n2);
• Add item in index: array.splice(index, 0, item);
• What is this in JavaScript?

  function foo() {
    // not real syntax!!! ⚠
    if(foo is an ArrowFunction) doNothing; // Arrow functions inherit this from the parent scope
    else if(foo called with new) this = {};
    else if(
      foo called with apply ||
      foo called with call  ||
      foo called with bind  ||
    ) this = thisArg
    else if(foo called within an object) this = thatObject
    else if(strictMode){
      this = undefined
    } else{
      // default binding, last resort
      this = window;
      // or global in node
    }
  }

• Fetch JSON syntax:

  fetch(url + '?<query-params>', {
    method: 'GET',
    headers: {
      'Content-Type': 'application/json',
    },
  })
    .then((response) => response.json())
    .then((json) => console.log(json));

• Classes in JavaScript

Reactjs

Vuejs

• onclick: @click="doSomething()"
• for: v-for="(item, index) in items"
• two way binding: v-model="property"
• two way binding inside for: v-model="items[index].property"

Java

Apache Server

AEM

• Get ContextHub userType: JSON.parse(localStorage.getItem('ContextHubPersistence')).store['usertypes-jsonp'].userType
• Create a new project using the Maven archetype

  mvn -X -B archetype:generate \
   -D archetypeGroupId=com.adobe.aem \
   -D archetypeArtifactId=aem-project-archetype \
   -D archetypeVersion=27 \
   -D appTitle="AEM Test" \
   -D appId="test" \
   -D groupId="com.test"
   -D aemVersion=6.5.7
  

Git

Command Line

• Find: find <path> -name "<blob>" e.g. find /home/username/ -name "*.log”
• Find text: grep -lro <text-to-find> <path>
• Find current working directory of a running process: lsof -p <PID> | grep cwd
• Get directory size: du -sh <path>
• Get public IP: curl -s checkip.dyndns.org | sed -e 's/.*Current IP Address: //' -e 's/<.*$//'
• scp:
  • scp your_username@remotehost.edu:foobar.txt /some/local/directory
  • scp foobar.txt your_username@remotehost.edu:/some/remote/directory
• Recursively change group: chgrp -R GROUPNAME DIRECTORY-OR-PATH

VIM

• Delete all lines: :1,$d
• Delete line :dd
• Go to end of line: :$
• Display line numbers: :set number