Key takeaways for useEffect

useEffect-key-takeaways.js

useEffect(fn) // run function on every render
useEffect(fn, []) // run function only when the component is first rendered
useEffect(fn, [value]) //run function when component is first rendered and when the `value` changes

// Remember if you pass dependency(value) which is an object - React perform
// strict comparision using "===" of the first level properties and will not
// conduct comparisons deeper into the properties.