object contains code example

Example 1: javascript does object have property

var person = {'first_name': 'bill','age':20};

if ( person.hasOwnProperty('first_name') ) {
    //person has a first_name property
}

Example 2: hasOwnProperty

The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property (as opposed to inheriting it).

const object1 = {};
object1.property1 = 42;

console.log(object1.hasOwnProperty('property1'));
// expected output: true

console.log(object1.hasOwnProperty('toString'));
// expected output: false

Example 3: js does object contain value

// You can turn the values of an Object into an array.
// Then test that a value is present:

// This assumes, that the Object is not nested
// and the value is an exact match:

var obj = { a: 'test1', b: 'test2' };

// Note that an array can only have positive index's; so
// checking for a negative index is a super valid way for getting a
// boolean value as a result for the check.
if (Object.values(obj).indexOf('test1') > -1) {
   console.log('Value exists!');
}

Example 4: javascript object includes

const person = {
  first_name: "Sam",
  last_name: "Bradley"
};

Object.values(person).includes("Bradley");

Example 5: object contains property javascript

if (x.hasOwnProperty('y')) {}

//or

if ('y' in x) {}

//or

if (x?.y){}

Example 6: check if field exists in object javascript

if ('field' in obj) {
}