更改HTML <input> 通过javascript图片，无法调用方法addEventListener

Question

我正在尝试获取输入图像，以在单击时通过javascript进行更改，但通过Google Chrome调试得到以下错误：

Uncaught TypeError: Cannot call method 'addEventListener' of undefined 

以下是我的HTML代码：

<section id="skin">
<video id="mainPlayer" width="640" height="360">
    <source src="video.mp4">
</video>
<nav>
    <div id="buttons">
        <input type="image" src="play_button.png" id="playButton" width="22" height="22">
    </div>
    <div id="defaultBar">
        <div id="progressBar"></div>
    </div>
    <div style="clear:both"></div>
</nav>

这是我的JavaScript代码：

function doFirst() {
    mainPlayer = document.getElementById('mainPlayer');
    playButton = document.getElementsByName('playButton')[0];

    playButton.addEventListener('click', playOrPause, false);
}

function playOrPause() {
    if (!mainPlayer.paused && !mainPlayer.ended) {
    mainPlayer.pause();
    playButton.src="controls.png";
    window.clearInterval(updateBar);
} else {
    mainPlayer.play();
    playButton.src="play_button.png"
    updateBar = setInterval(update, 500);
    }
}

window.addEventListener('load',doFirst,false);

Answer 1

playButton = document.getElementsByName（'playButton'）[0]; 你会在这里得到一个空数组

您需要在输入标签中添加名称属性或更改为

playButton = document.getElementById('playButton');