Find key or value presence in object

const targetToLookFor: string = "targetKey";

const someObject = {
  "key1": "val1",
  "key2": "val2",
  "targetKey": "val3"
};

const result = Object.keys(someObject).find(key => targetToLookFor == key);
// returns "targetKey"
// `undefined` returned when not found

Extract Values from Array of Objects (JSON)

Extracting key or values from Objects.

// input array of objects
const data = [
  { foo: 1, bar: 2},
  { foo: 3, bar: 4},
  { foo: 5, bar: 6}
];

const foosFromData = items.map(record => record.foo);
const foosFromData2 = items.map(({ foo }) => foo);

// Output: [1, 3, 5]

Check if Object is empty

const someObject = {};

const isObjectEmpty: Boolean = Object.entries(someObject).length === 0;