@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

Name	Description	Example
args	An array with all arguments, which were submitted to log function.	"foo" in args
debug	Value of LogType.Debug.	type == debug
default	Value of LogType.Default.	type == default
error	Value of LogType.Error.	type == error
false	Value of false.	isDebug == false
info	Value of LogType.Info.	type == info
isDebug	Indicates if type has value of LogType.Debug.	isDebug and type == debug
isDefault	Indicates if type has value of LogType.Default.	isDefault and type == default
isError	Indicates if type has value of LogType.Error.	isError and type == error
isInfo	Indicates if type has value of LogType.Info.	isInfo and type == info
isTrace	Indicates if type has value of LogType.Trace.	isTrace and type == trace
isWarn	Indicates if type has value of LogType.Warn.	isWarn and type == warn
null	Value of null.	arg0 != null
severity	type as string in lower case characters.	severity in ("debug", "default", "error", "info", "trace", "warn")
trace	Value of LogType.Trace.	type == trace
true	Value of true.	isError == true
type	A value of LogType.	type not in (debug, trace)
undefined	Value of undefined.	arg0 != undefined
warn	Value of LogType.Warn.	type == warn

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

Name	Description	Example
concat(..args: any[])	Handles a list of arguments as strings and concats them to one without using a separator.	concat("Tanja", " M.") == "Tanja M."
day(useLocalTimeOrTimezone: boolean | string)	Returns the current day of the current month.	day() >= 1 and day() <= 31
endOf(value: any, unit: string, useLocalTimeOrTimezone: boolean | string)	Returns a value, which represents the end of a time area.	endOf(now(), "day") >= now()
every(value: any, ...args: any[])	Handles a value as string and checks if all arguments are included.	every("foo Bar Bazz", "foo", "Bar", "Baz")
hour(useLocalTimeOrTimezone: boolean | string)	Returns the current hour.	hour() >= 0 and hour() <= 23
isFalsy(val: any)	Checks if a value is falsy.	isFalsy(arg0)
isNil(val: any)	Checks if a value is null or undefined.	isNil(arg0)
isNull(val: any)	Checks if a value is null.	isNull(arg0)
isoWeek(useLocalTimeOrTimezone: boolean | string)	Returns the current ISO week.	isoWeek() >= 1 and isoWeek() <= 53
isoWeekday(useLocalTimeOrTimezone: boolean | string)	Returns the current ISO weekday.	isoWeekday() >= 1 and isoWeekday() <= 7
isTruthy(val: any)	Checks if a value is truthy.	isTruthy(arg0)
isUndefined(val: any)	Checks if a value is undefined.	isUndefined(arg0)
item(arr: any, key: any = 0)	Returns the value of an array-like object.	item(args, 1) == "foo"
join(seperator: any, ..args: any[])	Handles a list of arguments as strings and joins them to one, using a separator.	join(" + ", "MK", "TM") == "MK + TM"
len(val: any)	Returns the length of a value.	len("foo") == 3 and len(args) >= 1
log(val: any, returnValue: any = true)	Logs a value.	log(args)
lower(val: any)	Handles a value as string and converts its characters to lowercase.	lower("FoO") == "foo"
ltrim(val: any)	Handles a value as string and removes leading whitespace characters.	ltrim(" foo ") == "foo "
minute(useLocalTimeOrTimezone: boolean | string)	Returns the current minute.	minute() >= 0 and minute() <= 59
month(useLocalTimeOrTimezone: boolean | string)	Returns the current month.	month() >= 1 and month() <= 12
ms(useLocalTimeOrTimezone: boolean | string)	Returns the current milliseconds.	ms() >= 0 and ms() <= 999
now(useLocalTimeOrTimezone: boolean | string)	Returns the UNIX timestamp of the current time.	log(now())
regex(val: any, pattern: string, flags: string = "i")	Handles a value as string and checks for a regular expression.	regex("Foo Bar Bazz", "(bar)")
rtrim(val: any)	Handles a value as string and removes ending whitespace characters.	rtrim(" foo ") == " foo"
second(useLocalTimeOrTimezone: boolean | string)	Returns the current second.	second() >= 0 and second() <= 59
some(value: any, ...args: any[])	Handles a value as string and checks if a least one argument is included.	some("bar FoO BAZZ", "FoO", "BAR", "baz")
startOf(value: any, unit: string, useLocalTimeOrTimezone: boolean | string)	Returns a value, which represents the start of a time area.	startOf(now(), "day") <= now()
str(value: any)	Converts a value to a string, which is not null and not undefined.	str(0) == "0"
trim(val: any)	Handles a value as string and removes leading and ending whitespace characters.	trim(" foo ") == "foo"
typeOf(value: any)	Returns the type of a value.	log(typeOf(arg0)) and typeOf(args) == "array" and typeOf(null) == "null" and typeOf("foo") == "string"
upper(val: any)	Handles a value as string and converts its characters to uppercase.	upper("fOo") == "FOO"
year(useLocalTimeOrTimezone: boolean | string)	Returns the current year.	year() == 1979 and month() == 9 and day() == 5

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.