https://jsfiddle.net/sz479ecd/

destructure-example.js

///// an exercise in object and array destructuring
// https://gist.github.com/timabell/0757735a759ed086fc57f51014392587
// https://jsfiddle.net/sz479ecd/

// object and array destructuring example
let sourceObject = {
  propertyA: 2,
  propertyB: [3, 4, 5],
  z: 99,
};
let {
  propertyA: output1, // map property into new variable (seems backwards to me but that's how it is)
  output2 = 6, // default for missing prop
  propertyB: [
    output3, // capture first array element
    ...rest // dots capture remaining array elements
  ] = [], // default input to empty array to avoid "TypeError: (intermediate value).propertyB is undefined" if no input array
  z, // make variable that matches property name
} = sourceObject || {}; // or default empty object to avoid "TypeError: sourceObject is undefined" if nothing passed in
console.log(output1, output2, output3, rest, z)

// again but with no source object so the defaults kick in
sourceObject = undefined;
( // surround with bracket because without the let it's not recognised as destructuring
  {
    propertyA: output1,
    output2 = 6,
    propertyB: [
      output3,
      ...rest
    ] = []
  } = sourceObject || {});
console.log([output1, output2, output3, rest.length, rest[0], rest[1]])