Failed to execute 'readAsText' on 'FileReader': parameter 1 is not of type 'Blob'

const fileInput = fileDropzone1.files;

if (fileInput.length === 0) {
    console.log("No file selected.");
} else {
    const file = fileDropzone1.value[0];
    const reader = new FileReader();

    reader.onload = function(event) {
        const content =;
        const digitSum = Array.from(content)
            .filter(char => /\d/.test(char))
            .reduce((sum, digit) => sum + parseInt(digit), 0);
        console.log("Sum of Digits:", digitSum);


I want to run a script that takes in some files, evaluates data and outputs some new files.
The code above should take a file and sum the numbers in it. I want to return the value calculated first before moving to the next stage of creating an output file.

The error here is Failed to execute 'readAsText' on 'FileReader': parameter 1 is not of type 'Blob'.  but the string  provided  by fileDropzone1.value[0] appear to be an encoded blob.

Hi @Chilaka

Thanks for reaching out!


Is a base64 encoded value for the file that is uploaded

For accessing the numbers in the file, you could use Papa.parse --

something like Papa.parse(atob(fileComponentName.values[0] ) )

Or, you could use our built in parse functionality: