Calling FileWrite.write returns Type Error

[canhduckhong]

Bug Report

Problem

I got this error when trying to write a binary string into file.

this._realReader.readAsArrayBuffer is not a function. 
(In 'this._realReader.readAsArrayBuffer(file)', 
'this._realReader.readAsArrayBuffer' is undefined)

The error is thrown at FileReader.js, line 302.

FileReader.prototype.readAsArrayBuffer = function (file) {
    if (initRead(this, file)) {
        return this._realReader.readAsArrayBuffer(file);
    }
    const totalSize = file.end - file.start;
    readSuccessCallback.bind(this)('readAsArrayBuffer', null, file.start, totalSize, function (r) {
        const resultArray = (this._progress === 0 ? new Uint8Array(totalSize) : new Uint8Array(this._result));
        resultArray.set(new Uint8Array(r), this._progress);
        this._result = resultArray.buffer;
    }.bind(this));
}; 

Here is how I call the FileWriter in my code:

writeBlobToFile = (file: FileEntry, blob): angular.IPromise<void> => {
        return this.$q((resolve, reject) => {
            file.createWriter((fileWriter) => {
                fileWriter.write(blob);
                fileWriter.onwriteend = resolve;
                fileWriter.onerror = reject;
            }, reject);
     });
};

Environment, Platform, Device

iOS 17.6 and iOS 18.0
iPhone 13 Plus

Version information

cordova-plugin-file version 8.1.0
cordova-ios version 7.1.0

[breautek]

It would be interesting to see in your environment what is being returned by:

cordova-plugin-file/www/FileReader.js

Line 27 in 03a4f4c

const origFileReader = modulemapper.getOriginalSymbol(window, 'FileReader');

Because the only way

this._realReader.readAsArrayBuffer is not a function.
(In 'this._realReader.readAsArrayBuffer(file)',
'this._realReader.readAsArrayBuffer' is undefined)

makes sense is if

cordova-plugin-file/www/FileReader.js

Line 43 in 03a4f4c

this._realReader = origFileReader ? new origFileReader() : {}; // eslint-disable-line new-cap

uses the false condition and assigns _realReader to {} which obviously has no methods and would explain the "readAsArrayBuffer is not a function ... readAsArrayBuffer is undefined"

[canhduckhong]

Unfortunately I cannot reproduce the issue in my local environment. It is on a user device.
It is obvious
modulemapper.getOriginalSymbol(window, 'FileReader');
returns a falsy value.
It can be due to the modulemapper cannot find FileReader in the window object.
I wonder if we can have a fallback strategy for this.