script.js

$(document).ready(function(){
  //---canvas
  var canvas = document.getElementById("canvas");
  var ctx = canvas.getContext("2d");
  //---square
  var squareCentreX;
  var squareCentreY;
  var squareDim = 400;
  var square = {x:0, y: 0, dx: 0, dy: 0};
  //---controls
  var side = getRandomInt(1, 4);
  var newSquare = true;
  //
  var score = 0;
  var speed = 60;
  var interval;


  document.addEventListener("keydown", keyDownHandler, false);
  canvas.addEventListener("click", clicked, false);

  function mobileCheck() {//https://stackoverflow.com/questions/11381673/detecting-a-mobile-browser
    var check = false;
    (function(a){if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino/i.test(a)||/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(a.substr(0,4))) check = true;})(navigator.userAgent||navigator.vendor||window.opera);
    return check;
  }

  //adjustments for mobile
  if(mobileCheck()){
    $("#para").css("fontSize", "20px");
    $("#canvas").resizeCanvas(750, 800);
  }

  squareCentreX = canvas.width/2;
  squareCentreY = canvas.height/2;


  function keyDownHandler(e) {
    if(e.keyCode == 32){
      clicked();
    }
  }

  function clicked(){
    newSquare = true;
    side = getRandomInt(1, 4);
    if(inBounds()){
      //level up
      score++;
      speed = speed/1.2;
      //make bounds smaller
      squareDim -= 10;
    }
    else if(score > 0){
      score--;
      //make box bigger
      squareDim += 5;
      speed = speed*1.2;
    }
    if(squareDim <= 30){
      winner();
    }
  }

  function getRandomInt(min, max) {
      return Math.floor(Math.random() * (max - min + 1)) + min;
  }

  function drawSquare() {
    ctx.beginPath();
    ctx.rect(squareCentreX-squareDim/2, squareCentreY-squareDim/2, squareDim, squareDim);//x, y, w, h
    ctx.fillStyle = "#2980B9";
    ctx.strokeStyle = "rgba(0, 0, 255, 0.5)";
    if(mobileCheck()){
      ctx.lineWidth = 10;
    }
    else{
      ctx.lineWidth = 3;
    }
    ctx.stroke();
    ctx.closePath();
  }

  function drawScore() {
    ctx.fillStyle = "#0095DD";
    if(mobileCheck()){
      ctx.font = "30px Arial";
      ctx.fillText("Score: "+score, 8, 35);
    }
    else{
      ctx.font = "16px Arial";
      ctx.fillText("Score: "+score, 8, 20);
    }
  }

  function draw() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    drawSquare();
    drawScore();
    makeMovingSquare(side);
    clearInterval(interval);
    interval = setInterval(draw, speed);
  }

  function makeMovingSquare(side) {
    var size;
    if(mobileCheck()){
      size = 25;
    }
    else{
      size = 12;
    }
    ctx.beginPath();
    if(newSquare){
      if(side === 1){//left side
        square.x = size
        square.y = canvas.height/2
        square.dx = 5;
        square.dy = 0;
      }
      else if (side === 2) {//top
        square.x = canvas.width/2
        square.y = size
        square.dx = 0;
        square.dy = 5;
      }
      else if (side === 3) {//right side
        square.x = canvas.width - size;
        square.y = canvas.height/2
        square.dx = -5;
        square.dy = 0;
      }
      else if (side === 4) {//bottom
        square.x = canvas.width/2;
        square.y = canvas.height-size;
        square.dx = 0;
        square.dy = -5;
      }
      newSquare = false;
    }
    ctx.rect(square.x, square.y, size, size);
    ctx.fillStyle = "#e74c3c";
    ctx.fill();

    //bounds checking
    if(square.x + square.dx > canvas.width-size/2){//hits right side
      square.x = 0 + size;
    }
    else if(square.x + square.dx < size/2) {//hits left side
      square.x = canvas.width - size;
    }
    else if(square.y + square.dy > canvas.height-size/2) { //hits bottom
      square.y = 0 + size;
    }
    else if(square.y + square.dy < size/2){//hits top
      square.y = canvas.height - size;
    }

    square.x += square.dx;
    square.y += square.dy;

    ctx.closePath();
  }


  function inBounds(){
    if(square.x >= squareCentreX-(squareDim/2) && square.x <= squareCentreX+(squareDim/2)){
      if(square.y >= squareCentreY-(squareDim/2) && square.y <= squareCentreY+(squareDim/2)){
        return true;
      }
    }
    return false;
  }

  function winner(){
    alert("You won!");
    document.location.reload();
    squareCentreX = canvas.width/2;
    squareCentreY = canvas.height/2;
    squareDim = 400;
    square = {x:0, y: 0, dx: 0, dy: 0};
    newSquare = true;
    score = 0;
    speed = 60;

  }

  interval = setTimeout(draw, speed);


});

(function($) { //https://stackoverflow.com/questions/11368477/dynamically-resize-canvas-window-with-javascript-jquery
        $.fn.extend({
            //Let the user resize the canvas to the size he/she wants
            resizeCanvas:  function(w, h) {
                var c = $(this)[0]
                c.width = w;
                c.height = h
            }
        })
    })(jQuery)