Check if object is Array of instance of specific object in Node.JS

Question

I have a simple class in Node JS

class Animal {
 constructor(name) {
 this.name = name;
 // more fields ...
 }
}
let objects = [];
objects.push(new Animal('Dog'));
objects.push(new Animal('Cat'));
objects.push(new Animal('Dinosaur'));
console.log(objects);

What's the best way to check if this array is instanceof Animal objects , without looping over and checking instanceof of each element ?

• ikhvjs: Your question is not clear. check if this array is instanceof Animal objects Do you mean check if this array only contains instanceof Animal objects ?
• JAN: @ikhvjs: Exactly!
• ikhvjs: Then, you still need to loop over all elements in the array for checking.

Answer 1

Use Array.prototype.every():

class Animal {
 constructor(name) {
 this.name = name;
 // more fields ...
 }
}
let objects = [];
objects.push(new Animal('Dog'));
objects.push(new Animal('Cat'));
objects.push(new Animal('Dinosaur'));
console.log(objects.every(x => x instanceof Animal));

• Jamiec: Just to be clear, this still loops over every item in the array
• Guerric P: Indeed, and it's not possible without looping