====== Javascript Promises ======
Very details article about promises: https://web.dev/promises/

===== Fact =====
  - Support by Chrome 32, Opera 19, Firefox 29, Safari 8 & Microsoft Edge, and up
  - A Promise can be chained with ''.then(CALL_BACK_FUNCTION(VARIABLE){...})'' and ,''catch(CALL_BACK_FUNCTION(VARIABLE){...})''
  - .then(...), and .catch(...) return type of Promise
  - A Promise can either be ''fulfilled or rejected'', so the ''.then(...)'' can actually take up to 2 call-back functions, the first one for fulfill, and the second one for rejection call-back. Like:<code>
 fetch("https://api.example.com/items")
      .then(res => res.json())
      .then(
        (result) => {
          this.setState({
            isLoaded: true,
            items: result.items
          });
        },
        (error) => {
          this.setState({
            isLoaded: true,
            error: error
          });
        }
      )
</code>
  - .catch(...) is the syntactic sugar for ''then(undefined, CALL_BACK_FUNCTION(VARIABLE){...})''
  - The rejection call-back (second functional parameter of a Promise), and the .catch(...) are **different**! If we do .then(function(result){...}, function(error){...}), either one of them will be called. For .catch(...) if anything in the chain before it it rejected without a rejection call-back, any .then(...) in between will be skip, and the .catch(...) will be called.