exports.write = function()

in src/browser/FileProxy.js [236:286]
39 lines of code
10 McCabe index (conditional complexity)

        exports.write = function (successCallback, errorCallback, args) {
            const fileName = args[0];
            let data = args[1];
            const position = args[2];
            const isBinary = args[3]; // eslint-disable-line no-unused-vars

            if (!data) {
                if (errorCallback) {
                    errorCallback(FileError.INVALID_MODIFICATION_ERR);
                }
                return;
            }

            if (typeof data === 'string' || data instanceof String) {
                data = new Blob([data]);
            }

            exports.getFile(function (fileEntry) {
                let blob_ = fileEntry.file_.blob_;

                if (!blob_) {
                    blob_ = new Blob([data], { type: data.type });
                } else {
                    // Calc the head and tail fragments
                    const head = blob_.slice(0, position);
                    const tail = blob_.slice(position + (data.size || data.byteLength));

                    // Calc the padding
                    let padding = position - head.size;
                    if (padding < 0) {
                        padding = 0;
                    }

                    // Do the "write". In fact, a full overwrite of the Blob.
                    blob_ = new Blob([head, new Uint8Array(padding), data, tail],
                        { type: data.type }
                    );
                }

                // Set the blob we're writing on this file entry so we can recall it later.
                fileEntry.file_.blob_ = blob_;
                fileEntry.file_.lastModifiedDate = new Date() || null;
                fileEntry.file_.size = blob_.size;
                fileEntry.file_.name = blob_.name;
                fileEntry.file_.type = blob_.type;

                idb_.put(fileEntry, fileEntry.file_.storagePath, function () {
                    successCallback(data.size || data.byteLength);
                }, errorCallback);
            }, errorCallback, [fileName, null]);
        };