javascript - 在 JavaScript 中单击按钮时下载按钮和输入字段没有响应

Question

我创建了一个表单，使用 php、sql 和 JavaScript 显示数据库中的图像。完整代码如下:

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<link rel="stylesheet" type="text/css" href="style.css">




<div class="container">
  <div style="margin-top: 5%;" class="row">

    <?php
            require('db_config.php');
$id=$_GET['editid'];

            $sql = "SELECT * FROM image_gallery where id='$id'";
            $images = $mysqli->query($sql);


            while($image = $images->fetch_assoc()){


            ?>
      <div class="col-md-5"><canvas id="imageCanvas"></canvas></div>



      <div style="margin-left: 2%;" class="col-md-5">


        <div class="modal-content">
          <div class="modal-header">
            <h4 class="something">
              <?php echo $image['title']; ?>
            </h4>
            <div class="modal-body">


              <form method="post" action="">
                <div class="row">
                  <div class="col-md-12">
                    <input type="text" id="name" placeholder="Name" required />
                  </div>
                  <div class="col-md-12">
                    <input id="download" class="mebutton" type="button" name="button" value="Download">
                  </div>
                </div>
              </form>



            </div>
          </div>
        </div>

      </div>

  </div>
</div>





<script type="text/javascript">
  var text_title = "Heading";

  var canvas = document.getElementById('imageCanvas');
  var ctx = canvas.getContext('2d');
  var img = new Image();
  // img.crossOrigin = "anonymous";

  window.addEventListener('load', DrawPlaceholder)

  function DrawPlaceholder() {
    img.onload = function() {
      DrawOverlay(img);
      DrawText(text_title);
      DynamicText(img)
    };
    img.src = 'uploads/<?php echo $image['
    image ']  ?>';

  }

  var canvas = document.getElementsByTagName('canvas')[0];
  canvas.width = 500;
  canvas.height = 500;


  function DrawOverlay(img) {

    ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, canvas.width, canvas.height);


    ctx.fillStyle = 'rgba(230, 14, 14, 0)';
    ctx.fillRect(0, 0, canvas.width, canvas.height);
  }

  function DrawText(text) {
    ctx.fillStyle = "black";
    ctx.textBaseline = 'middle';
    ctx.font = "50px 'Montserrat'";
    ctx.fillText(text, 50, 50);
  }

  function DynamicText(img) {
    document.getElementById('name').addEventListener('keyup', function() {
      ctx.clearRect(0, 0, canvas.width, canvas.height);
      DrawOverlay(img);
      text_title = this.value;
      DrawText(text_title);
    });
  }


  document.getElementById('download').onclick = function download() {
    convertToImage();
  }
</script>


<?php } ?>

问题是表单没有响应，当我将其留空时，输入字段没有显示“必填”错误，并且按钮也没有响应。我的代码有什么问题？

Answer 1

<form method="post" action="" id="form_name">
                <div class="row">
                  <div class="col-md-12">
                    <input type="text" id="name" placeholder="Name" required />
                  </div>
                  <div class="col-md-12">
                    <input id="download" class="mebutton" type="submit" name="button" value="Download">
                  </div>
                </div>
              </form>


<script>
$("#form_name").submit(function(){

    convertToImage();
return false

});

</script>