@slimlib/niceties NPM

Niceties

Experimental logger/reporter for async tasks.

Provides API for reporting async events that can be later handled by cutom appender.

Provides default appender that uses console for output.

Installation

yarn add niceties

npm install --save niceties

Example

import { niceties } from 'niceties';

const logger = niceties();

try {
    logger.start('starting something');
    ...
    // some async code
    ...
    logger.success('finished something');
} catch(e) {
    logger.fail('finished something');
}

API

Main entry point for logger:

function niceties(tag?: string): {
    start(message: string, loglevel?: LogLevel | undefined): void;
    update(message: string, loglevel?: LogLevel | undefined): void;
    success(message: string, loglevel?: LogLevel | undefined): void;
    fail(message: string): void;
};

Will return a logger instance that can be viewed as an entry for a single async task. tag can be used to distinguish between async tasks (will be provided to appender).

start(message: string, loglevel?: LogLevel | undefined): void;

Emits start event inside a logger. If loglevel provided it will be remembered and used as default loglevel in subsequent events in the same logger instance. Default loglevel (if argument is not provided) is info.

update(message: string, loglevel?: LogLevel | undefined): void;

Emits update event. Can be used to inform user that we are doing something else in the same async task. loglevel used to redefine default loglevel.

success(message: string, loglevel?: LogLevel | undefined): void;

Emits success event. Can be used to inform user that task succesfully finished. loglevel used to redefine default loglevel.

fail(message: string): void;

Emits fail event. Can be used to inform user that task finished and failed. loglevel is always error.

Log levels

const enum LogLevel {
    verbose, // for debugging logs, not for displaying on screen in normal cases
    info, // should be printed to user but not an error
    warn, // something is probably wrong, but we can continue
    error // operation completely failed
}

Setting another appender

User or another library can set another appender by calling:

function setAppender(appender: Appender);

where appender is a function with following type

(message: LogMessage) => void

const enum Action {
    start,
    update,
    success,
    fail
}

interface LogMessage {
    inputId: number;
    loglevel: LogLevel;
    message: string;
    action: Action;
    tag?: string;
}