JavaScript cheat sheet/reference guide generator for web development (for beginners)

javascript-study-guide.js

// Paste this into the console, and it'll console.log a quick overview of all the methods
// that any beginning JavaScript programmer should know!

// Tip: Run this somewhere like https://www.example.com/ so that the website's global
// variables don't show up here.

{
const test = function () {
const analysed = new Map()
const entries = function * (obj) {
  for (const key of Object.getOwnPropertyNames(obj)) {
    yield [key, obj[key]]
  }
  for (const key of Object.getOwnPropertySymbols(obj)) {
    yield [`[${key.description}]`, obj[key]]
  }
}
const alphabet = 'abcdefghijklmnopqrstuvwxyz'
function analyse (name, obj) {
  if (obj === null) {
    return [name + ' : null']
  } else if (typeof obj === 'function' || typeof obj === 'object') {
    const arr = []
    if (analysed.get(obj)) {
      return [`${name} === ${analysed.get(obj)}`]
    }
    analysed.set(obj, name || 'globalThis')
    if (typeof obj === 'function') {
      if (obj.prototype) {
        const base = name ? name + '#' : ''
        for (const [k, v] of entries(Object.getOwnPropertyDescriptors(obj.prototype))) {
          if (v.value) {
            arr.push(...analyse(base + k, v.value))
          } else {
            arr.push(base + k + ' : getter')
          }
        }
      } else {
        return [`${name} : function(${[...alphabet.slice(0, obj.length)].join(', ')})`]
      }
    } else {
      for (const [k, v] of entries(obj)) {
        const key = k[0] === '['
          ? name + k
          : name
          ? name + '.' + k
          : k
        arr.push(...analyse(key, v))
      }
      if (arr.length === 0) {
        arr.push(`${name} : ${obj[Symbol.toStringTag] || obj.constructor.name}`)
      }
    }
    return arr
  } else {
    return [`${name} : ${typeof obj}`]
  }
}
console.log(analyse('', globalThis).sort().join('\n'))
}
// setTimeout used to avoid showing console API functions
setTimeout(eval(test))
}

Revision 1

Initial revision.

Revision 2

Avoid duplicating globalThis (globalThis was incorrectly cached)

Revision 3

Do not show globals from the command line API; avoid polluting the global namespace

Revision 4

Show argument count for functions

Revision 5

Alphabetise everything

Revision 6

Empty objects will now show their prototype

Revision 7

Show prototype name of objects with no owned properties; better symbol property key name display