Answers for "javascript check if object not have property"

how to check wether the property exist in a object in java script

if (obj.hasOwnProperty('prop')) {
    // do something
}

js check if object has property

const object1 = new Object();
object1.property1 = 42;

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

javascript check if object property exists

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

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