test: fix RegExp nits

* Remove needless RegExp flag

  In fixed case, `/g` flag is needless in the boolean context.

* Remove needless RegExp capturing

  Use non-capturing grouping or remove capturing completely when:

  * capturing is useless per se, e.g. in test() check;
  * captured groups are not used afterward at all;
  * some of the later captured groups are not used afterward.

* Use test, not match/exec in boolean context

  match() and exec() return a complicated object,
  unneeded in a boolean context.

* Do not needlessly repeat RegExp creation

  This commit takes RegExp creation out of cycles and other repetitions.

  As long as the RegExp does not use /g flag and match indices,
  we are safe here.

  In tests, this fix hardly gives a significant performance gain,
  but it increases clarity and maintainability,
  reassuring some RegExps to be identical.

  RegExp in functions are not taken out of their functions:
  while these functions are called many times
  and their RegExps are recreated with each call,
  the performance gain in test cases
  does not seem to be worth decreasing function self-dependency.

PR-URL: https://github.com/nodejs/node/pull/13770
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/test/parallel/test-string-decoder.js b/test/parallel/test-string-decoder.js
index 8de0f7ba16..87ab5e8d37 100644
--- a/test/parallel/test-string-decoder.js
+++ b/test/parallel/test-string-decoder.js
@@ -144,6 +144,7 @@ function test(encoding, input, expected, singleSequence) {
   } else {
     sequences = [singleSequence];
   }
+  const hexNumberRE = /.{2}/g;
   sequences.forEach((sequence) => {
     const decoder = new StringDecoder(encoding);
     let output = '';
@@ -155,7 +156,7 @@ function test(encoding, input, expected, singleSequence) {
       const message =
         'Expected "' + unicodeEscape(expected) + '", ' +
         'but got "' + unicodeEscape(output) + '"\n' +
-        'input: ' + input.toString('hex').match(/.{2}/g) + '\n' +
+        'input: ' + input.toString('hex').match(hexNumberRE) + '\n' +
         'Write sequence: ' + JSON.stringify(sequence) + '\n' +
         'Full Decoder State: ' + inspect(decoder);
       assert.fail(output, expected, message);