const transformer = {
fraction: 'Autobots',
hasOwnProperty() {
return 'Decepticons!';
},
};
// output: 'Decepticons'
console.log(transformer.hasOwnProperty('fraction'));
// output: true
console.log(Object.hasOwn(transformer, 'hasOwnProperty'));August 5th, 2022
A safe way to check if an object has a specific property, is to use Object.hasOwn. It is possible to do the same with Object.prototype.hasOwnProperty, but the problem is, that the object could have it's own proerty named hasOwnProperty.
const decepticons = ['Megatron', 'Starscream', 'Blitzwing'];
const lastDecepticon = decepticons.at(-1);
console.log(lastDecepticon); // output: 'Blitzwing'August 4th, 2022
To get the last item of an array, we had to write array[array.length-1]. A shorter way is to use the at() method.
class Transformer {
#transform() {
console.log('Fancy sound! 🎶');
}
canTransform() {
return #transform in this;
}
}
const optimusPrime = new Transformer();
console.log(optimusPrime.canTransform()); // trueAugust 3rd, 2022
We can use the in operator to check if an object has a given private property.
class transformer {
name: 'Optimus Prime';
#previousName: 'Orion Pax'; // private attribute
rollOut() {
//...
}
// private method
#transform() {
//...
}
}August 2nd, 2022
Until now, the convention was to use the _ for private attributes and methods. However, this had not been able to prevent the abuse.
To declare a private attribute or method, just put a # in front of it.
class Autobot {
name = 'Optimus Prime';
fraction = 'Autobots';
}
const transformer = new Autobot();
// output: I am Optimus Prime and leader of the Autobots!
console.log(`I am ${transformer.name} and leader of the ${transformer.fraction}!`);August 1st, 2022
In object-oriented programming, class attributes are often declared in the constructors. In JS, no constructor is needed.