CodeLenny / fit-writer

Write fit exercise files

Fit Writer

A TypeScript-powered library to write FIT files.

Table of Contents

• Features

Features

fit-writer uses the pairing of definition messages with one or more data messages (the foundation of the FIT format) to drive the API design.

const file = new FitFile();

const header = new FitRecordDefinition<[
    FitFields.file_id.type, FitFields.file_id.manufacturer,
    FitFields.file_id.product, FitFields.file_id.serial_number,
]>(
    FitFields.file_id.type.createDefinition(),
    FitFields.file_id.manufacturer.createDefinition(),
    FitFields.file_id.product.createDefinition(),
    FitFields.file_id.serial_number.createDefinition(),
);
file.add(header);
file.add(header.create(
    FitFields.file_id.type.activity(),
    FitFields.file_id.manufacturer.development(),
    new FitNumber(22),
    new FitNumber(1234),
));

Re-use the same definition messages

Provide a single definition message, then create multiple data messages from that definition.

Strongly typed definition and data messages

The parameters when creating a new FitRecordDefinition or creating data messages must match the defined format. This means that your IDE and compiler can both complain if you don’t provide all the fields defined, or if the fields aren’t in the correct order.

Field values are strongly typed

You can’t pass a string to a number field. Enum fields require specific members.

Record structure is enforced

You can’t use fields only allowed in the file_id record inside activity records.

Editor support for parameters

Your editor may be able to describe the desired parameters, and perform smart autocompletion with variables that match the desired types.

Example