调试：第 126 行：语法错误意外结束

Question

我在第 126 行的 JS/HTML5 pong 游戏项目中收到错误：

tennisJS_game.html:126 Uncaught SyntaxError: Unexpected end of input

我看不出哪里出错了。我关闭了函数，其他一切看起来都很好。

下面是我的代码

var canvas;
var canvasContext;
var ballX = 50;
var ballY = 50;
var ballSpeedX = 10;
var ballSpeedY = 4;

var paddle1Y = 250;
const PADDLE_HEIGHT = 100; 
// C Programming #define (ALWAYS CONSTANT)

/*
Observing returning event (evt) of mouse positioning coordinates in relation to where the mouse is on the "gameCanvas"
For example starting point on the "gameCanvas" is on (0,0) on the (y,x) axis
EventListener wouldn't care about mouse position or "mousePos" if this code wasn't here
Two piece of data are being returned here... mouseX and mouseY
*/

function calculateMousePos(evt) {
    var rect = canvas.getBoundingClientRect();
    var root = document.documentElement;
    var mouseX = evt.clientX - rect.left - root.scrollLeft;
    var mouseY = evt.clientY - rect.top - root.scrollTop;
    return {
        x:mouseX,
        y:mouseY
        };

}

//variables section


//Speed of objects & EventListener & Resetting the Ball section

window.onload = function () {
    canvas = document.getElementById('gameCanvas');
    canvasContext = canvas.getContext('2d');

    var framesPerSecond = 30;
    setInterval(function() {
        moveEverything();
        drawEverything();
      }, 1000/framesPerSecond );

    canvas.addEventListener('mousemove',
        function(evt) {
            var mousePos = calculateMousePos(evt);
            paddle1Y = mousePos.y-(PADDLE_HEIGHT/2); //So players mouse and paddle relationship position is center
            });
}

function moveEverything() {
    ballX = ballX + ballSpeedX;
    ballY = ballY + ballSpeedY
    if(ballX < 0) {
        if(ballY > paddle1Y &&
        ballY < paddle1Y+PADDLE_HEIGHT) {
                ballSpeedX = -ballSpeedX;
        } else {
        ballReset();    }

    if(ballX > canvas.width) {
        ballSpeedX = -ballSpeedX;
    }

    if(ballY < 0) {
        ballSpeedY = -ballSpeedY;
    }
    if(ballY > canvas.height) {
        ballSpeedY = -ballSpeedY;
    }

//Speed of objects & EventListener & Resetting the Ball section


function colorRect(leftX,topY,width,height,drawColor) {
    canvasContext.fillStyle = drawColor;
    canvasContext.fillRect(leftX,topY, width, height);
}

//Ball Reset f(x) section

function ballReset() {
     ballSpeedX = -ballSpeedX;
    ballX = canvas.width/2;
    ballY = canvas.height/2;
}



//Ball Reset f(x) section



//canvas arguments/parameters

function drawEverything () {

    // next line blanks out the screen with black
    colorRect(0,0,canvas.width,canvas.height,'black');

    // this left player paddle
    colorRect(0,paddle1Y,10,100,'white');

    // next line draws the ball
    colorCircle(ballX,ballY,10,'white');
}



function colorCircle(centerX,centerY,radius, drawColor) {
    canvasContext.fillStyle = drawColor;
    canvasContext.beginPath();
    canvasContext.arc(centerX,centerY,radius,0,Math.PI*2,true);
    canvasContext.fill();}



//canvas arguments/parameters

Answer 1

函数 moveEverything 的括号未正确关闭。 – Nehal J Wani 8 月 28 日 7:06

对于 if(ballX