我想做一个if声明，当用户点击时，每个图像都是全屏的。

<div class="image-container">
  <img src="image.jpg" alt="Image" onclick="toggleFullScreen(this)">
</div>

.image-container {
  position: relative;
  width: 100%;
  height: 100%;
}

.image-container img {
  width: 100%;
  height: auto;
  cursor: pointer;
}

.full-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 9999;
}

function toggleFullScreen(image) {
  if (image.classList.contains('full-screen')) {
    exitFullScreen();
  } else {
    enterFullScreen(image);
  }
}

function enterFullScreen(image) {
  if (image.requestFullscreen) {
    image.requestFullscreen();
  } else if (image.mozRequestFullScreen) {
    image.mozRequestFullScreen();
  } else if (image.webkitRequestFullscreen) {
    image.webkitRequestFullscreen();
  } else if (image.msRequestFullscreen) {
    image.msRequestFullscreen();
  }
  image.classList.add('full-screen');
}

function exitFullScreen() {
  if (document.exitFullscreen) {
    document.exitFullscreen();
  } else if (document.mozCancelFullScreen) {
    document.mozCancelFullScreen();
  } else if (document.webkitExitFullscreen) {
    document.webkitExitFullscreen();
  } else if (document.msExitFullscreen) {
    document.msExitFullscreen();
  }
  // 在退出全屏时，需要将所有图像的样式重置为原始状态
  var images = document.querySelectorAll('.image-container img');
  images.forEach(function(image) {
    image.classList.remove('full-screen');
  });
}