ES2015 Destructuring Assignment Example -- Basic function argument destructuring assignment with default value

arguments-basic-defaults.js

/* ES5 equivalent (ignoring assignment of intended falsy values)
  function foo(one, two) {
    one = one || 1;
    console.log({one, two});
  }
 */
function foo(one = 1, two) {
  console.log({one, two});
}

foo(); // { one: 1, two: undefined }
foo('FOO'); // { one: 'FOO', two: undefined }
foo(undefined, 'BAR'); // { one: 1, two: 'BAR' }