javascript object check if property exists code example

Example 1: How to tell if an attribute exists on an object

const user = {
    name: "Sicrano",
    age: 14
}

user.hasOwnProperty('name');       // Retorna true
user.hasOwnProperty('age');        // Retorna true
user.hasOwnProperty('gender');     // Retorna false
user.hasOwnProperty('address');    // Retorna false

Example 2: javascript does object have property

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

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

Example 3: test if property exists javascript

const hero = {
  name: 'Batman'
};

hero.hasOwnProperty('name');     // => true
hero.hasOwnProperty('realName'); // => false

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