examples of some new (and older) features of JS

es6CodeSnippets

let test = ["Nikola", "Aleksandra", "Andreja", "Luka"]

let name1, name2, name3, name4;


[name1, name2, name3, name4] = [...test]
console.log(name4) // Luka


const result = test.reduce((x,y) => x + y, "")

const joined = test.join("")

const filtered = test.filter( name => name < "Marko")

const mapped = test.map( name => name.padStart(15, "***"))

console.log(result) // NikolaAleksandraAndrejaLuka
console.log(filtered) // [ 'Aleksandra', 'Andreja', 'Luka' ]
console.log(mapped) // [ '*********Nikola', '*****Aleksandra', '********Andreja', '***********Luka' ]
console.log(joined) // NikolaAleksandraAndrejaLuka

// async example

<script>
    function breathe(amount) {
      return new Promise((resolve, reject) => {
        if (amount < 500) {
          reject('That is too small of a value');
        }
        setTimeout(() => resolve(`Done for ${amount} ms`), amount);
      });
    }

    function catchErrors(fn) {
      return function (...args) {
        return fn(...args).catch((err) => {
          console.error('Ohhhh nooo!!!!!');
          console.error(err);
        });
      }
    }

    async function go(name, last) {
      console.log(`Starting for ${name} ${last}!`);
      const res = await breathe(1000);
      console.log(res);
      const res2 = await breathe(300);
      console.log(res2);
      const res3 = await breathe(750);
      console.log(res3);
      const res4 = await breathe(900);
      console.log(res4);
      console.log('end');
    }

    const wrappedFunction = catchErrors(go);

    wrappedFunction('Andrej', 'Rasevic');
  </script>
  
// generator example

const inventors = [
    { first: 'Albert', last: 'Einstein', year: 1879 },
    { first: 'Isaac', last: 'Newton', year: 1643 },
    { first: 'Galileo', last: 'Galilei', year: 1564 },
    { first: 'Marie', last: 'Curie', year: 1867 },
    { first: 'Johannes', last: 'Kepler', year: 1571 },
    { first: 'Nicolaus', last: 'Copernicus', year: 1473 },
    { first: 'Max', last: 'Planck', year: 1858 },
  ];

  function* loop(arr) {
    console.log(inventors);
    for (const item of arr) {
      yield item;
    }
  }

  const inventorGen = loop(inventors);
  
  
// Custom Promise example
const p = new Promise((resolve, reject) => {
   //setTimeout(() => {
     //reject(Error('Err Throwing an error to reject'));
   //}, 1000);
   setTimeout(() => {
     resolve('asycn is where it is at!!');
   }, 1000);
 });

 p
   .then(data => {
     console.log(data);
   })
   .catch(err => {
     console.error(err);
   });


function breathe(amount) {
    return new Promise((resolve, reject) => {
      if (amount < 500) {
        reject('That is too small of a value');
      }
      setTimeout(() => resolve(`Done for ${amount} ms`), amount);
    });
  }