ES6+ notes

  • Async functions
  • Arrow functions
    const foo = (x, y) => { return x + y; };
  • Classes
  • const
    const foo = "foo";
  • Default parameters
    const foo = (x, y = 1) => { return x + y; };
  • filter
    [1, 2, 3, 4, 5].filter(n => n < 3); // [1, 2]
  • for-of loop
    for (let item of items) {console.log(item)}
  • import / export
    export default defaultExport;
import defaultExport from "module-name";
export function exportFunction(){...};
import { exportFunction } from "module-name";
  • let
    let foo = "foo";
  • Promises
    const promise1 = new Promise(function(resolve, reject) {
  setTimeout(function() {
    resolve('foo');
  }, 300);
});

promise1.then(function(value) {
  console.log(value); // foo
});
  • reduce
    const array1 = [1, 2, 3, 4];
const reducer = (accumulator, currentValue) => {
  return accumulator + currentValue;
}
console.log(array1.reduce(reducer)); // 10
  • Set
    const set1 = new Set([1, 2, 3]);
console.log(set1.has(1)); // true
console.log(set1.has(2)); // true
console.log(set1.has(3)); // true

set1.add(4)
console.log(set1.has(4)); // true

set1.delete(4)
console.log(set1.has(4)); // false
console.log(set1.size); // 3
  • Spread
    function sum(x, y, z) {
  return x + y + z;
}

const numbers = [1, 2, 3];

console.log(sum(...numbers)); // 6
  • Template literals (Template strings)
    • `string text`
    `string text line 1
     string text line 2`
    `string text ${expression} string text`