Question

This is my code：

 document.getElementsByName('submitButton').onclick = function(event) {
  event.preventDefault();

  var num1 = parseFloat(document.getElementsByName('valueA')[0].value),
      num2 = parseFloat(document.getElementsByName('valueB')[0].value),
      arithmeticOperator = document.getElementsByName('arithmeticOperator')[0].value,
      output = document.getElementsByName('result');

  switch(arithmeticOperator) {
    case '+':
        result = num1 + num2;
        break;
    case '-':
        result = num1 - num2;
        break;
    case '*':
        result = num1 * num2;
        break;
    case '/':
        if(num2 != 0)
        {
            result = num1 / num2;
        }else {
            result = 'Dela inte med 0!';
        }
        break;
    default:
        result = 'Error';
  }
  window.alert(result);
  return false;
};

我的问题是我无法获取代码来生成带答案的弹出窗口。当我在我的HTML中使用ID它工作正常但我想学习getElementsByName如何工作。所以，我根本不想改变我的HTML，但我需要帮助我的JS。

Answer 1

getElementsByName返回一个类似于object的数组，因此您需要通过索引获取元素并添加侦听器

"http :// site.com/image.png" // from Web
"file:///mnt/sdcard/image.png" // from SD card
"file:///mnt/sdcard/video.mp4" // from SD card (video thumbnail)
"content://media/external/images/media/13" // from content provider
"content://media/external/video/media/13" // from content provider (video thumbnail)
"assets://image.png" // from assets
"drawable://" + R.drawable.img // from drawables (non-9patch images)

注意：在您的页面中，我无法看到具有所述名称的按钮

由于您有表单，最好使用表单的提交事件

            imageLoader.displayImage(
            Uri.fromFile(new java.io.File(FILE_PATH)).toString()
            ,
            markableImageView, mDio,
            new SimpleImageLoadingListener() {
                @Override
                public void onLoadingStarted(String imageUri, View view) {
                }

                @Override
                public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
                }

                @Override
                public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
                    if (loadedImage != null & view != null) {
                        ((ImageView) view).setImageBitmap(Bitmap.createScaledBitmap(
                                loadedImage,
                                mContext.getResources().getInteger(R.integer.width_file_view),
                                mContext.getResources().getInteger(R.integer.height_file_view),
                                false));
                    }
                }
            }, new ImageLoadingProgressListener() {
                @Override
                public void onProgressUpdate(
                        String imageUri, View view, int current, int total) {
                }
            });

演示：Fiddle

我想在我的代码中使用getElementsByName

1 个答案: