get keys of object js

1var foo = {
2  'alpha': 'puffin',
3  'beta': 'beagle'
4};
5
6var keys = Object.keys(foo);
7console.log(keys) // ['alpha', 'beta'] 
8// (or maybe some other order, keys are unordered).

1let person = {
2  firstname: 'John',
3  lastname: 'Doe'
4}
5
6console.log(person.firstname);
7// expected output: "John"
8
9delete person.firstname;
10
11console.log(person.firstname);
12// expected output: undefined

1myObject = {
2	"key": "value"
3}
4
5Object.keys(myObject); // get array of keys

1myObject = {
2	"key": "value",
3    "key2":"value2"
4}
5Object.keys(myObject);
6//console.log(Object.keys(myObject))   = ["key", "key2"]

1const object1 = {
2  a: 'somestring',
3  b: 42,
4  c: false
5};
6
7console.log(Object.keys(object1));
8// expected output: Array ["a", "b", "c"]

1var buttons = {
2  foo: 'bar',
3  fiz: 'buz'
4};
5
6for ( var property in buttons ) {
7  console.log( property ); // Outputs: foo, fiz or fiz, foo
8}