@egomobile/log-filter v0.1.4

@egomobile/log-filter

Extension for js-log with utilities to handle extended filters.

Install

Execute the following command from your project folder, where your package.json file is stored:

npm install --save @egomobile/log-filter

The following modules are defined in peerDependencies and have to be installed manually:

• @egomobile/log

Usage

Quick example

import log from "@egomobile/log";
import { withFilterExpression } from "@egomobile/log-filter";

// only warning or errors
const expression = 'severity == "warn" or severity == "error"';

log.use(withFilterExpression(expression));

// will log
log.warn("foo");
log.error("foo");

// will not log:
log("foo");
log.debug("foo");
log.info("foo");
log.trace("foo");

Syntax

The syntax is described here.

Constants

Additionally there will also dynamic constants be added, based on the number of arguments, which are submitted to a log function:

// arg0 == "foo" and message0 == "foo"
// arg1 == 42 and message1 == "42"
// arg2 == false and message2 == "false"
// arg3 == null and message3 == ""
// arg4 == undefined and message4 == ""
log("foo", 42, false, null, undefined);

It is also possible to add extra constants:

import log, { LogType } from "@egomobile/log";
import {
  IGetExtraLogFilterConstantsContext,
  LogFilterConstants,
  withFilterExpression,
} from "@egomobile/log-filter";

const expression =
  'foo == 42 and lowerMessage1 == "foo bar baz" and upperSeverity == "WARN" and error == undefined';

log.use(
  withFilterExpression(expression, {
    getExtraConstants: ({ type, args }: IGetExtraLogFilterConstantsContext) => {
      const extraConstants: LogFilterConstants = {
        // static value
        foo: 42,
        // functions will be handled as getters
        upperSeverity: () => LogType[type].toUpperCase(),
        // remove constant
        error: undefined,
      };

      // add extra and dynamic constants
      // lowerMessage<index + 1>
      // with lowercase values of items
      // of 'args'
      args.forEach((a, index) => {
        extraConstants[`lowerMessage${index + 1}`] = String(a).toLowerCase();
      });

      return extraConstants;
    },
  })
);

// should log
log.warn("FOO BAR BAZ");

// should not log
log("FOO BAR BAZ");
log.warn("FUH BAR BAZZ");

Functions

It is possible, to add or remove functions:

import log from "@egomobile/log";
import { withFilterExpression } from "@egomobile/log-filter";

const str = (val: any) => String(val);
const repeatStr = (val: any, count: number) => str(val).repeat(count);

const expression = 'repeatStr(arg0, 5) == "TM+MK TM+MK TM+MK TM+MK TM+MK "';

log.use(
  withFilterExpression(expression, {
    extraFunctions: {
      // new, custom function
      repeatStr,
      // overwrite existing function
      str,

      // remove these
      ltrim: undefined,
      rtrim: undefined,
    },
  })
);

// will log
log("TM+MK ");
// will not log
log("foo");

Credits

The module makes use of:

• Day.js
• Filtrex by Michal Grňo

Documentation

The API documentation can be found here.