Just a quick WoL sender for Deno I wrote a while ago (may be broken nowadays)

Deno-WoL.ts

/**
 * Author: Aroop Roelofs <me@finlaydag33k.nl>
 * License: Do Whatever You Want With it
 */
import { Buffer } from "https://deno.land/std/io/mod.ts";

interface IWolOptions {
  recipient?: IRecipient;
}

interface IRecipient {
  address: string;
  port: number;
}

export default class WakeOnLan {
  private packet: any;

  constructor(mac: string){
    this.packet = this.magic(mac);
  }

  /**
   * Create our magic packet.
   * 
   * @param mac 
   * @returns unknown
   */
  private magic(mac: string) {
    // Define some constants
    const macRepeat = 16;
    const macLength = 0x06;
    const header = 0x06;

    //Make sure our MAC is valid
    const parts = mac.match(/[0-9a-f-A-F]{2}/g);
    if(!parts || parts.length !==  macLength) throw new Error(`MAC address "${mac} is malformed!`);

    // Create a new buffer for our packet and add our header to it
    let packet = Buffer.alloc(header);

    // Create a new buffer from our MAC
    const macBuf = Buffer.from(parts.map((p: any) => parseInt(p, 16)));

    // Fill our packet with ones
    packet.fill(0xff);

    // Add all bytes of our MAC to the packet
    for(let i = 0; i < macRepeat; i++) {
      packet = Buffer.concat([packet, macBuf]);
    }

    // Return our packet
    return packet;
  }

  /**
   * Send our WOL packet to whom it may concern
   * 
   * @param options 
   */
  public wake(options: IWolOptions = {}) {
    // Assign our address and port
    // Broadcast if no recipient address or port are specified
    const { address, port } = Object.assign({
      address: '255.255.255.255',
      port: 9
    }, options.recipient);

    // Create a UDP socket
    const socket = Deno.listenDatagram({port: port, transport: "udp"});

    // Add event handlers to our socket
    socket.on('error', (err: Error) => {
      socket.close();
      throw err;
    });
    
    // Enable broadcasting
    socket.once('listening', () => {
      socket.setBroadcast(true);
    });

    // Send our packet
    socket.send(
      this.packet, 
      0, 
      this.packet.length, 
      port,
      address,
      (err: any, res: any) => {
        if(res !== this.packet.length) throw new Error(`Result and packet length mismatch!`);
        if(err) throw err;
        socket.close();
      }
    );
  }
}