ES5/6 Observer 👀

observer.js

/*
  ES5/6 Observer 👀
  ---
  - Like a promise (sort of) but will work in older browsers
  - With Babel, this will transpile to something very similar to want is written 
  - Note the error
  - both callback, err will return empty strings by default
  - bool is false by default
*/
const observer = (bool = false, callback = () => '', iterator = 10, maxTime = 300, err = () => '') => {
  const mT = maxTime
  const it = iterator

  let i, interval

  const observe = () => {
    i += 1
    // keep trying
    if (bool === false && i < maxTime) return 
    // fail and warn
    else if (i > maxTime) {
      console.warn(`${bool} is false`)
      return err()
    }
    // clear interval because bool is now true
    // success callback 
    clearInterval(interval)
    callback()
  }
  interval = setInterval(observe, 10)
}

observer.md

ES5/6 Observer

As browsers become more advanced, javascript engineering practices are stepping away from while loops and set intervals. However, if an older browser must be supported, have a simple observer to use can be beneficial to not be dependent on transpiling, etc.

observer.while.js

/*
  ES5/6 Observer w/ While loop 👀
  ---
  - Like a promise (sort of) but will work in older browsers
  - With Babel, this will transpile to something very similar to want is written 
  - Note the error
  - both callback, err will return empty strings by default
  - bool is false by default
*/

const observer = (bool = false, callback = () => '', maxSeconds = 3, err = () => '') => {
  const mS = maxSeconds
  const it = iterator
  const timer = new Date();
  
  let incomplete
  
  while (!incomplete) {
    const secondsPassed = timer.getSeconds()
    if (secondsPassed > mS || bool) incomplete = true
    if (bool) return callback() 
    else if (secondsPassed > mS && bool === false) {
      console.warn(`${bool} is false`)
      return err()
    }
  }
}