JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id="canvas" width="1350" height="600">Sorry, your browser doesn't support this</canvas>

CSS

#canvas { background-color: black; }

JavaScript

var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var lives = 3;

var Enemy = function (x, y, velx, vely,transparency,speed) {
    this.x = x;
    this.y = y;
    this.velx = 0;
    this.vely = 0;
    this.speed = speed;
    this.transparency = 1;
};

Enemy.prototype.update = function () {
    var tx = 650 - this.x;
    var ty = 250 - this.y;
    var dist = Math.sqrt(tx * tx + ty * ty);
    this.velx = (tx / dist)* this.speed;
    this.vely = (ty / dist)* this.speed;
    var distround = Math.floor(dist);
    if (distround > 0) {
        this.x += this.velx;
        this.y += this.vely;
    } else if (this.transparency != 0){
      alert("You lose!");
      location.reload(true);
    }
};

Enemy.prototype.isOnEnemy = function(x, y) {
    return (x >= this.x && x < this.x + 25 &&  // 25 = width
            y >= this.y && y < this.y + 25);   // 25 = height
};

Enemy.prototype.render = function () {
    context.fillStyle = 'rgba(255,255,255,'+this.transparency+')';
    context.fillRect(this.x, this.y, 25, 25);
};

var main = function(speed){
var enemies = [];
for (var i = 0; i < 10; i++) {
    // random numbers from 0 (inclusive) to 100 (exclusive) for example:
    var randomX = Math.random() * 896;
    var randomY = Math.random() * 1303;
    if (randomX > 100 && randomX < 1200) {
        if (randomX % 2 === 0) {
            randomX = 140;
        } else {
            randomX = 1281;
        }
    }
    if (randomY > 100 && randomY < 75) {
        if (randomY % 2 === 0) {
            randomY = 15;
        } else {
            randomY = 560;
        }
    }
    var enemy = new Enemy(randomX, randomY, 0, 0,1,speed);
    enemies.push(enemy);
}
for (var i = 0; i < 15; i++) {
    // random numbers from 0 (inclusive) to 100 (exclusive) for example:
    var randomX = Math.random() * 200;
    var randomY = Math.random() * 403;
    if (randomX > 100 && randomX < 1200) {
        if (randomX % 2 === 0) {
            randomX = 140;
        }...