Timer logs

A minimalist NodeJS library, written in TypeScript, for logging code execution time and errors.

Designed to work well with Google Cloud logging, but useful for any application.

Fully documented with JSDoc(in .d.ts) and examples. Includes full typescript support.

Installation

npm install timer-logs

Usage

import { Timer } from 'timer-logs'

const webservice = async () => {
    const timer = new Timer({filename: 'webservice.ts'})
    timer.start('operation 1')
    await sleep(1000) // perform operation 1
    timer.next('operation 2')
    await sleep(2000) // perform operation 2
    timer.next('operation 3')
    await sleep(3000) // perform operation 2
    timer.flush()
}

Output:

{
  "severity": "INFO",
  "message": "Timer: 6025ms",
  "filename": "webservice.ts",
  "operation 1": 1010,
  "operation 2": 2000,
  "operation 3": 3014
}

Config options

You can specify more options when constructing the Timer object to customise the log output.

const timer = new Timer({
    filename: 'webservice.ts',
    label: 'Demo timer',
    details: {id: 'c69adf0e7ff8fddf8a93'},
    severity: 'ERROR'
})

{
  "severity": "ERROR",
  "message": "Demo timer: 61ms",
  "filename": "webservice.ts",
  "Demo timer": 61,
  "id": "c69adf0e7ff8fddf8a93"
}

Available methods

The most important function is timer.flush() which prints the log to the console. It uses information saved from all the other function calls including the constructor. This function call should go at the end of the function you are profiling.

Other functions

Start a new timer

timer.start('label for timer')

Start another timer, after the first one. (Stops the most recently started timer, and begins a new one)

timer.next('the next label you want to time')

End the most recently started timer. Is automatically called when flush is called if the most recently started timer has not been ended already.

timer.end()

To stop a specific timer by name, there are two options

const timer1 = timer.start('timer 1')
const timer2 = timer.start('timer 2')
// perform operations
timer.stop('timer 1') // similar to console.time()
timer2.stop() //doesn't require the label

Error logging

Custom error messages

timer.customError('Zero length list returned. Expecting at least 1 item')

Output:

{
  "severity": "ERROR",
  "message": "Zero length list returned. Expecting at least 1 item",
  "filename": "webservice.ts"
}

Postgres error handling

const queryResult = await pool.query(`SELECT NOW()`).catch(e => timer.postgresError(e))

Generic error handling

try {
    JSON.parse('asdfghjkl;')
} catch (e) {
    timer.genericError(e)
}

Output

{
  "severity": "ERROR",
  "errorMessage": "Unexpected token a in JSON at position 0",
  "errorName": "SyntaxError",
  "stackTrace": "SyntaxError: Unexpected token a in JSON at position 0\n    at JSON.parse (<anonymous>)\n    at Object.<anonymous> (C:\\Users\\webservice.js:6:10)\n    at Module._compile (node:internal/modules/cjs/loader:1109:14)\n    atObject.Module._extensions..js (node:internal/modules/cjs/loader:1138:10)\n    at Module.load (node:internal/modules/cjs/loader:989:32)\n    at Function.Module._load (node:internal/modules/cjs/loader:829:14)\n    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:76:12)\n    at node:internal/main/run_main_module:17:47",
  "filename": "webservice.ts"
}