Maf-error NPM | npm.io

maf-error

checkable errors

based on terror package

install

npm i maf-error

why?

errors usually checks with if

// } catch (error) {
    if (error instanceof TaskError) {

        if (error.code === 'some_error_code') {
            // action ...
        } else if (/* ... */) {
            // ...
        } else {
            // ...
        }

    } else {
        // ...
    }

// }

terror package allows check error type and code, but if is still here

// var TaskError = terror.create('TaskError', {SOME_CODE: 'some error code'});
// } catch (error) {

    error = TaskError.ensureError(error);

    if (TaskError.is(TaskError.CODES.SOME_CODE)) {
        // action ...
    } } else if (/* ... */) {
        // ...
    } else {
        // ...
    }

// }

With promises you can write promise chain using different classes, methods, apis with different error types.

And got all error handling in one catch function.

// some method: get all tasks in list

api.lists.get(listId)
    .then((list) => {
        return api.tasks.find({listId: list.id});
    })
    .then((tasks) => {
        res.json(tasks);
    })
    .catch((error) => {
        // here can get ListError, TaskError from apis
        // and other errors

        // and if checks here

        if (error instanceof ListError) {
            if (ListError.is(ListError.CODES.NOT_FOUND, error)) {
                res.status(404).json('not found');
            } else if (ListError.is(/* ... */)) {
                // ...
            } else {
                // ...
            }
        } else if (error instanceof TaskError) {
            // many if here
        } else {
            logger.error(error);
            res.status(500).json('server error');
        }

    });

too much if, too much code

using maf-error

require('maf-error/initGlobal');

// same method and  same promise chain
//
    .catch((error) => {

        Error.ensureCheckChain(error)
            .if(ListError, {
                [ListError.CODES.NOT_FOUND]: (error) => {
                    res.status(404).json('not found');
                },

                [ListError.CODES.FORBIDDEN]: (error) => {
                    // ...
                }
            })
            .if(TaskError, {
                // ...
            })
            .else((error) => {
                logger.error(error);
                res.status(500).json('server error');
            })
            .check();

    });

clean and simple imho