Prototype Design Pattern

class AIPrototype {
    constructor(prototype){
        this.name = prototype.name;
        this.type = prototype.type;
        this.brains = prototype.brains || this.generateBrains();
    }

    clone(){
        // NOTE: if any of these properties are not a primitive type you need to create a shallow or deep copy.
        // For example if `this.brains` would be an object all AI objects that are generated 
        // from this `clone` function would use brain.
        // Though that may be good as they would think as one.
        return new AI(this.name, this.type, this.brains)
    }

    generateBrains() {
        // super expensive operation
        const randomStringThatSimulatesBrainFunctionality = Math.random().toString(36).substring(7);
        return randomStringThatSimulatesBrainFunctionality
    }
}

class AI {
    constructor(name, type, brains) {
        this.name = name;
        this.type = type;
        this.brains = brains
    }
}

const prototype = new AI("GLaDOS", "rampant");
const rampantAIPrototype = new AIPrototype(prototype);

const rampantAIV1 = rampantAIPrototype.clone();
const rampantAIV2 = rampantAIPrototype.clone();

console.log(rampantAIV1.brains === rampantAIV2.brains) // true

class AI {
    constructor(name, type, brains){
        this.name = name;
        this.type = type;

        AI.prototype.brains = brains || this.generateBrains();
    }

    generateBrains() {
        // super expensive operation
        const randomStringThatSimulatesBrainFunctionality = Math.random().toString(36).substring(7);
        return randomStringThatSimulatesBrainFunctionality
    }
}

const rampantAI = new AI("GLaDOS", "rampant");

const friendlyAI = new AI("GLaDOS", "friendly");

console.log(rampantAI.brains === friendlyAI.brains) // true