whyIsItRecalculating.js

export const whyIsItRecalculating = (
    funcName,
    ...fieldNames
) => decoratedFunc => {
    let prevValues;
    return (...values) => {
        // eslint-disable-next-line no-console
        console.group(`whyIsItRecalculating ${funcName}`);
        if (prevValues) {
            if (prevValues.length < values.length) {
                // eslint-disable-next-line no-console
                console.log(
                    'received more values than last time: %d vs %d',
                    prevValues.length,
                    values.length
                );
            } else if (prevValues.length > values.length) {
                // eslint-disable-next-line no-console
                console.log(
                    'received less values than last time: %d vs %d',
                    prevValues.length,
                    values.length
                );
            }
            let i;
            for (i = 0; i < prevValues.length; i += 1) {
                if (prevValues[i] !== values[i]) {
                    // eslint-disable-next-line no-console
                    console.log(
                        `Argument ${i} ("${fieldNames[i] ||
                            'unknown'}") changed from`,
                        prevValues[i],
                        'to',
                        values[i]
                    );
                }
            }
        }
        // eslint-disable-next-line no-console
        console.groupEnd();

        prevValues = values;
        return decoratedFunc(...values);
    };
};