printable-characters

    

A little helper for handling strings containing zero width characters, ANSI styling, whitespaces, newlines, weird Unicode 💩 symbols, etc.

Determining the real (visible) length of a string

``javascript
const { strlen } = require ('printable-characters')

strlen ('foo bar') // === 7
strlen ('\u001b[106mfoo bar\u001b[49m') // === 7
`

Detecting blank text

`javascript
const { isBlank } = require ('printable-characters')

isBlank ('foobar') // === false
isBlank ('\u001b[106m \t \t \n \u001b[49m') // === true
`

Obtaining a blank string of the same width

`javascript
const { blank } = require ('printable-characters')

blank ('💩') // === ' '
blank ('foo') // === ' '
blank ('\tfoo \nfoo') // === '\t \n '
blank ('\u001b[22m\u001b[1mfoo \t\u001b[39m\u001b[22m')) // === ' \t'
`

Matching invisible characters

`javascript
const { ansiEscapeCodes, zeroWidthCharacters } = require ('printable-characters')

const s = '\u001b[106m' + 'foo' + '\n' + 'bar' + '\u001b[49m'

s.replace (ansiEscapeCodes, '') // === 'foo\nbar'
.replace (zeroWidthCharacters, '') // === 'foobar'
`

Getting the first N visible symbols, preserving the invisible parts

Use for safely truncating strings to maximum width without breaking ANSI codes:

`javascript
const { first } = require ('printable-characters')

const s = '\u001b[22mfoobar\u001b[22m'

first (s, 0) // === '\u001b[22m\u001b[22m'
first (s, 1) // === '\u001b[22mf\u001b[22m'
first (s, 3) // === '\u001b[22mfoo\u001b[22m'
first (s, 6) // === '\u001b[22mfoobar\u001b[22m'
`

Extracting the invisible parts followed by the visible ones (parsing)

`javascript
const { partition } = require ('printable-characters')

partition ('') // [ ])
partition ('foo') // [['', 'foo'] ])
partition ('\u001b[1mfoo') // [['\u001b[1m', 'foo'] ])
partition ('\u001b[1mfoo\u0000bar') // [['\u001b[1m', 'foo'], ['\u0000', 'bar'] ])
partition ('\u001b[1mfoo\u0000bar\n') // [['\u001b[1m', 'foo'], ['\u0000', 'bar'], ['\n', '']])
`

Applications

- as-table — a simple function that prints objects as ASCII tables
- string.bullet — ASCII-mode bulleting for the list-style data
- string.ify — a fancy pretty printer for the JavaScript entities
- Ololog! — a better console.log for the log-driven debugging junkies!

TODO

Handle multi-component emojis, as in this article:

`javascript
assert.equal (strlen ('👩‍❤️‍💋‍👩'), 1) // FAILING, see http://blog.jonnew.com/posts/poo-dot-length-equals-two for possible solution
assert.equal (blank ('👩‍❤️‍💋‍👩'), ' ') // FAILING, see http://blog.jonnew.com/posts/poo-dot-length-equals-two for possible solution
``