Constructor Stealing

Constructor stealing (or classical inheritance) involves calling the parent constructor inside the child constructor using call() or apply(). This allows the child to inherit the parent’s instance properties, but methods are not shared via the prototype.

Code Example

function Parent(name) {
  this.name = name;
  this.colors = ["red", "blue"];
}
Parent.prototype.greet = function () {
  console.log(`Hello ${this.name}`);
};

function Child(name) {
  Parent.call(this, name); // steal constructor
}

const child1 = new Child("John");
child1.colors.push("green");
console.log(child1.colors); // ["red", "blue", "green"]

const child2 = new Child("Jane");
console.log(child2.colors); // ["red", "blue"] (not affected)
// child1.greet(); // error: greet is not shared