doulin2025
doulin2025
2018-01-07 10:10

如何使用Javascript每秒加载图像[重复]

已采纳

This question already has an answer here:

I have programmed a web site in HTML/PHP/Javascript that must display the data stored in a MySQL database every second. It displays it as a graph (PNG image produced by running graph.php).

<!DOCTYPE html>

<html>
    <title>Live Tracking Run'INSA</title>
    
    <head>
        <script type = "text/javascript">
            function refresh() {
                document.getElementById('graph').src = 'graph.php';
            }
        </script>
    </head>

    <p><h2>Visualisation des données</h2></p>
    
    <body onLoad='setInterval(refresh, 1000);'>
        <img id='graph'/>
    </body>
    
</html>

visualiser.php displays the graph well, but graph.php does not update the last one as it is supposed to.

PS: The graph (made with pChart libraries) shows the heart rate as a function of time as well.

</div>
  • 点赞
  • 写回答
  • 关注问题
  • 收藏
  • 复制链接分享
  • 邀请回答

1条回答

  • dpppic5186 dpppic5186 3年前

    Fundamentally that looks fine. I suspect the image isn't being updated because the src isn't changing when you set it the second, third, etc. times. You could either clear it before setting it:

    function refresh() {
        var graph = document.getElementById('graph');
        graph.src = '';
        graph.src = 'graph.php';
    }
    

    ...or give it an ever-changing URL by appending a query string:

    function refresh() {
        document.getElementById('graph').src = 'graph.php?' + Date.now();
    }
    
    点赞 评论 复制链接分享