Generating alpha numeric characters in javascript

robot-name.ts

/**
 * Manage robot factory settings.
 * 
 * When robots come off the factory floor, they have no name.
 * 
 * The first time you boot them up, a random name is generated in the format
 * of two uppercase letters followed by three digits, such as RX837 or BC811.
 * 
 * Every once in a while we need to reset a robot to its factory settings,
 * which means that their name gets wiped. The next time you ask, it will
 * respond with a new random name.
 * 
 * The names must be random: they should not follow a predictable sequence.
 * Random names means a risk of collisions. Your solution must ensure that
 * every existing robot has a unique name.
 * 
 */
class RobotName {
    private _name = '';
    private readonly _characters: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    public static _GENERTED_NAMES = new Set();
    private readonly _MAX_YIELDS = 3;


    constructor() {        
        this.generateName();        
    }

    private generateName(): void{
        let rand: number = Math.random();
        let tempName: string = "";
        for(let i=0; i<this._MAX_YIELDS ; i++){
            rand = Math.floor((rand *1000 < 100)? rand * 10000:rand * 1000);
            tempName = this.getRandomChar(2) + rand        
            if(!RobotName._GENERTED_NAMES.has(tempName)){
                RobotName._GENERTED_NAMES.add(tempName);
                break; // break the loop here
            }
        }        
        this._name = tempName;                
    }

    
    private getRandomChar(length: number): string{
        let output = "";
        for(let i = 0; i<length; i++){
            output += this._characters.charAt(Math.floor(Math.random() * 26));
        }
        return output;
    }

    get name(): string{
        return this._name;
    }

    public resetName(): void{
        this.generateName();
    }

}

export default RobotName;