Tiny performance improvement by not compiling regular expression each time #3479
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lowerCase.js
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| @@ -19,8 +19,9 @@ import words from './words.js' | |||
| * lowerCase('__FOO_BAR__') | |||
| * // => 'foo bar' | |||
| */ | |||
| const rx = /['\u2019]/g | |||
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@nazar-pc Just curious, how does this effect the performance?
Im assuming that defining the regex before using it will eliminate the need for js to create a reference to it dynamically...
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Regular expressions take time to compile and additional time to execute upon some data. If you call lowerCase in a loop, regular expression will be compiled again and again on each call.
With proposed change it will be compiler once, thus each iteration will only involve executing pre-compiled regular expression, which is much faster.
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Can you rename the var to reQuotes.
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Done (commit amended)
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New version is constantly faster both in Firefox Nightly and Chromium Nightly: https://jsfiddle.net/dzym8svy/
Some projects call this function very often and performance hit can be significant in that case.