Object.prototype.hasOwnProperty) code example

Example 1: 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 2: hasownproperty.call

var foo = {
  hasOwnProperty: function() {
    return false;
  },
  bar: 'Here be dragons'
};

foo.hasOwnProperty('bar'); // always returns false

// Use another Object's hasOwnProperty
// and call it with 'this' set to foo
({}).hasOwnProperty.call(foo, 'bar'); // true

// It's also possible to use the hasOwnProperty property
// from the Object prototype for this purpose
Object.prototype.hasOwnProperty.call(foo, 'bar'); // true