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 ?

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 ? — ikhvjs
– ikhvjs, Commented Aug 26, 2021 at 8:40
Then, you still need to loop over all elements in the array for checking. — ikhvjs
– ikhvjs, Commented Aug 26, 2021 at 8:42

Guerric P · Accepted Answer · 2021-08-26 08:38:11Z

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));

answered Aug 26, 2021 at 8:38

Guerric P

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2 Comments

Jamiec Over a year ago

Just to be clear, this still loops over every item in the array

Guerric P Over a year ago

Indeed, and it's not possible without looping

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