Types

• 1.1 Primitives: When you access a primitive type you work directly on its value.

  • string
  • number
  • boolean
  • null
  • undefined

  • symbol

      const foo = 1;
      let bar = foo;
      bar = 9;
      console.log(foo, bar); // => 1, 9

  • Symbols cannot be faithfully polyfilled, so they should not be used when targeting browsers/environments that don’t support them natively.

• 1.2 Complex: When you access a complex type you work on a reference to its value.

  • object
  • array

  • function

      const foo = [1, 2];
      const bar = foo;
      bar[0] = 9;
      console.log(foo[0], bar[0]); // => 9, 9