Parameter 1 is not of type ‘blob’

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When you encounter the error message “parameter 1 is not of type ‘blob'”, it means that the first parameter you are passing in a certain context is expected to be of type ‘blob’ (binary large object), but it is not fulfilling that requirement.

A blob is a data type commonly used to store large amounts of binary data, such as images, videos, or audio files. In JavaScript, you can create a blob using the Blob constructor or by using the File or Blob objects obtained from user input or API calls.

To fix the error, you need to ensure that the first parameter you are passing is a valid blob object. Here are a few common scenarios that can lead to this error and their possible solutions:

  1. Missing or incorrect parameter type: Double-check the function or method signature and verify that the first parameter is indeed expected to be a blob. If it is, make sure you are passing a blob object or convert the input to a blob if necessary.


    // Example: Converting a base64-encoded string to blob
    const base64Data = '...'; // Base64-encoded string
    const contentType = 'image/jpeg'; // MIME type of the data
    const byteCharacters = atob(base64Data);
    const byteArrays = [];
    for (let i = 0; i < byteCharacters.length; i++) {
      byteArrays.push(byteCharacters.charCodeAt(i));
    }
    const byteArray = new Uint8Array(byteArrays);
    const blob = new Blob([byteArray], { type: contentType });
  2. Invalid file input: If you are trying to handle file uploads, ensure that the file input element is properly configured and that you are accessing the file object correctly. For example, if you are using the FileReader API, make sure you are calling the necessary methods to read and generate a blob from the file content.


    // Example: Reading a file input and generating a blob
    const fileInput = document.getElementById('file-input');
    const file = fileInput.files[0];
    const reader = new FileReader();
    reader.onloadend = function () {
      const blob = new Blob([reader.result], { type: file.type });
      // Further processing with the blob...
    }
    reader.readAsArrayBuffer(file);
  3. Unexpected data format: If you are receiving data from an external source, check if the data format matches the expected format. For example, if you are retrieving data from an API endpoint, ensure that the response data is in the correct format for conversion to a blob.

Understanding the specific context in which the error occurs and reviewing the relevant documentation or source code will help you identify the cause and apply the appropriate solution based on your use case.

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