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📜 Create mutable log lines into the terminal, and give life to your logs!

License: MIT License

JavaScript 100.00%

nodejs logging ansi-escape-codes console

node-draftlog's Introduction

Because Logging can be pretty and fun

Installation

$ npm install draftlog

What it does

It allows you to re-write a line of your log after being written. Just like post 'updating'. This is the building block for any dynamic element such as progress bars, loading status, animations, checkboxes and so on.

It does that by keeping track of the current lines of code written through the stream, and moving the cursor up to the line of the LogDraft you created previously, and updating its content.

Look in the examples folders to see how easy it is, to create anything. No strict and fixed widgets are given to you. Instead, use your creativity with this tool to create anything you want! Share the results later with an example ;)

Looking for CUTE Unicode chars? Check out Unicute.

How the HECK is that even possible?

Usage

// Setup
const DraftLog = require('draftlog')
DraftLog(console)

// Or, in a single line:
require('draftlog').into(console)

// Account for manual line breaks with:
require('draftlog').into(console).addLineListener(process.stdin)

To create a updatable log, use the draft method injected into the provided console:

// Create a Draft log
var update = console.draft('Hi, my name is')

// You can call logs after it
console.log('Something else')

// Use the received callback to update it as many times as you want
update('Hi, my name is Ivan!')

Here are some interesting examples:

// Prints a clock incrementing one every second in the same line
var draft = console.draft()
var elapsed = 1
setInterval( () => {
  draft('Elapsed', elapsed++, 'seconds')
}, 1000)

console.log('It doesn`t matter')
console.log('How \n many \n lines \n it uses')

Or maybe, to show an flow process?

function someAsyncFunction(){ 
  var TAG = '[someAsyncFunction]'
  var log = console.draft(TAG, 'init')

  function a() {
    setTimeout(() => {
      log(TAG, 'calling b')
      b()
    }, 500)
  }

  function b() {
    setTimeout(() => {
      log(TAG, 'finished')
    })
  }
}

You can create your own progress bar, just like "that":

require('draftlog').into(console)

// Input progess goes from 0 to 100
function ProgressBar(progress) {
  // Make it 50 characters length
  var units = Math.round(progress / 2)
  return '[' + '='.repeat(units) + ' '.repeat(50 - units) + '] ' + progress + '%'
}

var barLine = console.draft('Starting download...')
downloadFile(function (progress) {
  barLine(ProgressBar(progress))
})

// Will show something like: (being updated in realtime)
// [============================                      ] 56%

Learn from examples!

We have a few of them ready for you to use! Take a look at the examples folder. Remember to replace require('../') with require('draftlog').

Also, install chalk to get colors on your terminal ;)

Important things to know

Because of the way Terminals are built, it is not possible to update a text outside the viewing area of the terminal.

That said, DraftLogs are setup to automagically be rewritten on a new line if they reach the end of the viewport. Note that, you can disable that behavior, by setting DraftLog.defaults.canReWrite = false

Also, if the NodeJS environment cannot detect the number of rows of your terminal automatically, it will use the default height on DraftLog.defaults.maximumLinesUp. Modify that if needed.

When using into(console).addLineListener(process.stdin), your code will no longer exit automatically, because the stream is being "read". To stop your own code, you can call process.exit(0) or pause the stream when you want with: process.stdin.pause().

Discouragements

This library is awesome for development, cli tools and what ever you want to created, that is NOT an optimized "slave" server. Please, disable it passing true as a second parameter to the DraftLog initialization:

// Disable Initialization (true = production; false = development)
DraftLog(console, true)
// Or, with one line require-init:
require('draftlog').into(console, true)

Creator

Ivan Seidel

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node-draftlog's Issues

Proposals for new version

DraftLog works. The API is simple. I want to keep it that way, but it might be improved with a few ideas.

Please, contribute by giving your insights, ideas and so on.

`[1]` Avoid overriding `console._stdout`

Can we find a way to NOT put something in the middle of the Stream? Is it possible to 'listen' to data on a Writable stream? If so, that's all we need (we don't ever modify contents anyway)

`[2]` Should we 'hook' draft method into `console`?

Hooking into console is really cool, but... To specific.

What if the person doesn't uses console to do logging, but writing to stdout directly?
In that case, it would cause two problems:

Draft method would be available only through custom instantiated Console. That's a bad requirement to ask developers... (Console is cool, but not a requirement for logging stuff)
If any data get's logged directly into stdout, then it would not capture that data. [1] would fix that, if just in listening mode.

`[3]` Ideas for a new (and simpler) API

const DraftLog = require('draftlog')
console.draft = DraftLog(process.stdout[, process.stdin])
// Or save to a custom function maybe
const draft = DraftLog(process.stdout[, process.stdin])

// Would make things easier in case of disabling:
if (PRODUCTION) 
  const draft = DraftLog();

Question: Fix line at the bottom

First of all: Nice lib!

Now my question: Is it possible to fix a log at the bottom while I keep sending more console.logs?

I want to keep a status bar counting the number of downloads and failed downloads, while I keep submitting lines with the individual downloads

Typescript compatibility

Because this module extends functionality of Console, the following is required to avoid typescript complaining about missing "draft" function:

interface Console {
        draft: (a) => (b) => {}
}

I think to support this from the module level, we can use the global declaration feature

declare global {
    interface Console {
        draft: (a) => (b) => {}
    }
}

can't generate multiple lines

Let's say I have codes like this below:

let a = console.draft(' ')
let b = console.draft('')

setInterval(() => {
  a('something')
  b('something')
}, 1000)

It only shows a string.

Expose DraftLog instance's line on stdout stream

It may be useful to expose the line number whenever you update a draft console via console.draft()() so if we want to clear that line, we can use the line number without adding complex code to calculate it ourselves, as I see DraftLog._line contains the line, however it cannot be accessed via console.draft()()._line as console.draft() returns an new DraftLog(...).update.

Maybe you could add this simple thing by returning this._line in the update method.
Sorry about the big sentence above, I didn't know how to explain myself.

Or maybe a feature to clean the line completely could be added, as

DraftLog.update(); // or DraftLog.update('');

still leaves an empty line.

Thank you for your time, and sorry if this isn't something you want DraftLog to do.
Thanks for making such a great module. ✌️

Output seems to have a bug where some previous chars aren't deleted on update

When I run my timer for long enough, it seems to fail to re-render the line resulting in bizzare spelling issues that gradually become gibberish for each update. When the minute count no longer is necessary, the seconds from that format stick around as seen below.

Compatibility with Node repl module?

Here's a naive attempt at writing a Node REPL which shows the output of each command on the same line every time:

const repl = require('repl')
require('draftlog').into(console)
const update = console.draft('Starting REPL...')
repl.start({prompt:update})

And the output looks like this: https://asciinema.org/a/U0y4BMlqxMlhQLE2QE1szHiFi