先完成页面效果（HTML和CSS代码），再逐个给每个按钮添加事件，控制视频播放/暂停、进度和是否全屏等功能。

好的，下面是一个示例代码，其中包括一个视频和三个控制按钮：播放/暂停、全屏切换和音量控制。

HTML代码：

<div class="video-container">
  <video id="my-video" src="video.mp4"></video>
  <div class="controls">
    <button id="play-pause-btn">Play/Pause</button>
    <button id="fullscreen-btn">Fullscreen</button>
    <input id="volume-slider" type="range" min="0" max="1" step="0.1" value="1">
  </div>
</div>

CSS样式：

.video-container {
  position: relative;
  width: 640px;
  height: 360px;
}

video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.controls {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 50px;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
}

button {
  margin: 0 10px;
  background-color: transparent;
  border: none;
  color: #fff;
  font-size: 16px;
  cursor: pointer;
  outline: none;
}

input[type="range"] {
  width: 100px;
  height: 10px;
  margin: 0 10px;
  -webkit-appearance: none;
  background-color: #ddd;
  border-radius: 5px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px;
  height: 20px;
  background-color: #fff;
  border-radius: 50%;
  cursor: pointer;
}

JavaScript代码：

const video = document.getElementById("my-video");
const playPauseBtn = document.getElementById("play-pause-btn");
const fullscreenBtn = document.getElementById("fullscreen-btn");
const volumeSlider = document.getElementById("volume-slider");

// 播放/暂停
playPauseBtn.addEventListener("click", function() {
  if (video.paused) {
    video.play();
    playPauseBtn.textContent = "Pause";
  } else {
    video.pause();
    playPauseBtn.textContent = "Play";
  }
});

// 全屏切换
fullscreenBtn.addEventListener("click", function() {
  if (video.requestFullscreen) {
    video.requestFullscreen();
  } else if (video.mozRequestFullScreen) {
    video.mozRequestFullScreen();
  } else if (video.webkitRequestFullscreen) {
    video.webkitRequestFullscreen();
  }
});

// 音量控制
volumeSlider.addEventListener("input", function() {
  video.volume = volumeSlider.value;
});

这个示例代码演示了如何使用JavaScript控制HTML5视频的播放、暂停、全屏和音量。你可以根据自己的需要进一步扩展它。