javascript copy subset of properties code example

Example 1: js select keys from object

const object = { a: 5, b: 6, c: 7  };
const picked = (({ a, c }) => ({ a, c }))(object);

console.log(picked); // { a: 5, c: 7 }

Example 2: javascript subset of object array matching certain property

let cities = [
    {name: 'Los Angeles', population: 3792621},
    {name: 'New York', population: 8175133},
    {name: 'Chicago', population: 2695598},
    {name: 'Houston', population: 2099451},
    {name: 'Philadelphia', population: 1526006}
];

let bigCities = cities.filter(function (e) {  // filter function
    return e.population > 3000000;
});

//Output:
[
  { name: 'Los Angeles', population: 3792621 },
  { name: 'New York', population: 8175133 }
]