Bad output when used as a template tag on strings that contain an escape sequence

[noinkling]

Current behaviour

// Tab escape:

red(`foo\tbar`) // '\x1B[31mfoo\tbar\x1B[39m'
red`foo\tbar`   // '\x1B[31mfoo\\tbar\x1B[39m'

console.log(red(`foo\tbar`)) // foo	bar
console.log(red`foo\tbar`)   // foo\tbar

// Identity (pointless) escape:

red(`\p`) // '\x1B[31mp\x1B[39m'
red`\p`   // '\x1B[31m\\p\x1B[39m'

console.log(red(`\p`)) // p
console.log(red`\p`)   // \p

// Backslash escape:

red(`\\`) // '\x1B[31m\\\x1B[39m'
red`\\`   // '\x1B[31m\\\\\x1B[39m'

console.log(red(`\\`)) // \
console.log(red`\\`)   // \\

// Newline escape:

red(`foo\nbar`) // '\x1B[31mfoo\x1B[39m\n\x1B[31mbar\x1B[39m'
red`foo\nbar`   // '\x1B[31mfoo\x1B[39m\n\x1B[31mbar\x1B[39m' <- Hey it matches!

console.log(red(`foo\nbar`))
// foo
// bar
console.log(red`foo\nbar`)
// foo
// bar

// Backslash escape that happens to have an "n" after it:

red(`\\nice`) // '\x1B[31m\\nice\x1B[39m'
red`\\nice`   // '\x1B[31m\\\x1B[39m\n\x1B[31mice\x1B[39m' <- Oh no...

console.log(red(`\\nice`)) // \nice
console.log(red`\\nice`)
// \
// ice

Expected behaviour

Template tag result should be the same as the standard function call result.

Environment

• library version: 3.16.0

Additional context

I believe this line is the problem:

ansis/src/index.js

Line 43 in 4994864

? String.raw(arg, ...values).replace(/\\n/g, LF)

The "Motivation" section on the String.cooked ES proposal explains the issue: https://github.com/tc39/proposal-string-cooked?tab=readme-ov-file#motivation

In other words, I believe it can be fixed by changing to: String.raw({ raw: arg }, ...values) (without the newline replacement hack)

Appreciation for the useful project

• After the problem is resolved, do not forget to give a star ⭐

[webdiscus]

Hello @noinkling,

In other words, I believe it can be fixed by changing to: String.raw({ raw: arg }, ...values) (without the newline replacement hack)

Thanks for the suggestion. I'll make tests and release a beta version.

[webdiscus]

@noinkling the v4.0.0-beta.1 is released with the support of escape sequences in template literals.
Can you please check it?