Destructuring and Spread
Array Spread
Build a new array by spreading existing values.
Array Spread
spread_array.js
const extra = 4;
const joined = [...[1, 2], extra, 9].join(",");
const count = joined.split(",").length;
console.log("joined=" + joined);
console.log("count=" + count);
array-spread
Array spread copies values into a new array literal. It is often clearer than manual pushes when you are building a short derived list.