Allow exprs to contain the strings "$1" and "$2"

[paulrosenzweig]

We're having an issue in Metabase with translating strings that have dollar values in them. Curiously, it's only an issue if the amount started with a "1" or a "2".

The root cause was the behavior of String​.prototype​.replace(). When the first arg is a regexp, the second arg can reference captured groups. Since the relevant regex in ttag contained two capturing groups, $1 and $2 took on special meaning.

To fix that, I just changed them to non-capturing groups. This felt like the simplest solution, but there are two other options I considered:

1. We could escape the dollar signs in the replacement string (e.g. '$$1' rather than '$1').
2. Pass a function as the second argument to replace. This function should return the replacement string, but importantly the "$" replacement rules are not applied.

If we don't like the non-capturing group solution, I'd advocate for 2 over 1.

[codecov[bot]]

Codecov Report

Merging #171 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #171   +/-   ##
=======================================
  Coverage   98.18%   98.18%           
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  Files           4        4           
  Lines         495      495           
  Branches       76       76           
=======================================
  Hits          486      486           
  Misses          9        9

Impacted Files	Coverage Δ
src/utils.js	98.95% <100%> (ø)	:arrow_up:

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[AlexMost]

Hi @paulrosenzweig ! Seems like you have found an interesting case, I like the solution with a non capturing groups. Thanks for the PR!

[AlexMost]

The fix is available in 1.7.15 version. Please, let me know if that works!

[paulrosenzweig]

@AlexMost it worked! Thanks for the quick merge!