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88 lines
3.8 KiB
Markdown
88 lines
3.8 KiB
Markdown
# printable-characters
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[](https://travis-ci.org/xpl/printable-characters) [](https://coveralls.io/github/xpl/printable-characters) [](https://npmjs.com/package/printable-characters) [](https://scrutinizer-ci.com/g/xpl/printable-characters/?branch=master) [](https://david-dm.org/xpl/printable-characters)
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A little helper for handling strings containing zero width characters, ANSI styling, whitespaces, newlines, [weird Unicode 💩 symbols](http://blog.jonnew.com/posts/poo-dot-length-equals-two), etc.
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## Determining the real (visible) length of a string
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```javascript
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const { strlen } = require ('printable-characters')
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strlen ('foo bar') // === 7
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strlen ('\u001b[106mfoo bar\u001b[49m') // === 7
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```
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## Detecting blank text
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```javascript
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const { isBlank } = require ('printable-characters')
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isBlank ('foobar') // === false
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isBlank ('\u001b[106m \t \t \n \u001b[49m') // === true
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```
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## Obtaining a blank string of the same width
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```javascript
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const { blank } = require ('printable-characters')
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blank ('💩') // === ' '
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blank ('foo') // === ' '
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blank ('\tfoo \nfoo') // === '\t \n '
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blank ('\u001b[22m\u001b[1mfoo \t\u001b[39m\u001b[22m')) // === ' \t'
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```
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## Matching invisible characters
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```javascript
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const { ansiEscapeCodes, zeroWidthCharacters } = require ('printable-characters')
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const s = '\u001b[106m' + 'foo' + '\n' + 'bar' + '\u001b[49m'
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s.replace (ansiEscapeCodes, '') // === 'foo\nbar'
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.replace (zeroWidthCharacters, '') // === 'foobar'
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```
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## Getting the first N visible symbols, preserving the invisible parts
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Use for safely truncating strings to maximum width without breaking ANSI codes:
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```javascript
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const { first } = require ('printable-characters')
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const s = '\u001b[22mfoobar\u001b[22m'
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first (s, 0) // === '\u001b[22m\u001b[22m'
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first (s, 1) // === '\u001b[22mf\u001b[22m'
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first (s, 3) // === '\u001b[22mfoo\u001b[22m'
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first (s, 6) // === '\u001b[22mfoobar\u001b[22m'
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```
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## Extracting the invisible parts followed by the visible ones (parsing)
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```javascript
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const { partition } = require ('printable-characters')
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partition ('') // [ ])
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partition ('foo') // [['', 'foo'] ])
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partition ('\u001b[1mfoo') // [['\u001b[1m', 'foo'] ])
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partition ('\u001b[1mfoo\u0000bar') // [['\u001b[1m', 'foo'], ['\u0000', 'bar'] ])
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partition ('\u001b[1mfoo\u0000bar\n') // [['\u001b[1m', 'foo'], ['\u0000', 'bar'], ['\n', '']])
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```
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## Applications
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- [as-table](https://github.com/xpl/as-table) — a simple function that prints objects as ASCII tables
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- [string.bullet](https://github.com/xpl/string.bullet) — ASCII-mode bulleting for the list-style data
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- [string.ify](https://github.com/xpl/string.ify) — a fancy pretty printer for the JavaScript entities
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- [Ololog!](https://github.com/xpl/ololog) — a better `console.log` for the log-driven debugging junkies!
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## TODO
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Handle multi-component emojis, as in [this article](http://blog.jonnew.com/posts/poo-dot-length-equals-two):
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```javascript
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assert.equal (strlen ('👩❤️💋👩'), 1) // FAILING, see http://blog.jonnew.com/posts/poo-dot-length-equals-two for possible solution
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assert.equal (blank ('👩❤️💋👩'), ' ') // FAILING, see http://blog.jonnew.com/posts/poo-dot-length-equals-two for possible solution
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```
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