Package Exports

perf-regexes

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Readme

perf-regexes

Optimized and powerful regexes for JavaScript

Install

npm install perf-regexes --save

Regexes included matches...

Regex name	Description	Note
`JS_MLCOMM`	Valid multiline JS comment	Excludes invalid comments like `//`, supports nested `'/'`
`JS_SLCOMM`	Single line JS comment	From the `//` to the (but not including) next EOL
`JS_STRING`	Single and double quoted JS string	Handles nested quotes and escaped eols
`JS_DIVISOR`	Division operator and closing html tag	To skip non-regex slashes
`JS_REGEX`	Literal regex	It captures the last slash in `$1`
`HTML_COMM`	Valid HTML comments	HTML comments can be used in browsers with JavaScript
`ISCOMMENT`	The start of a comment	For both, HTML and JS comments, with no `g` option.

Except ISCOMMENT, all the regexes has the 'g' option and nothing more, so you can use it with exec or replace.

Please note that you don't need the 'm', pref-regexes works with Win/Mac/Unix EOLs with no problems, but if you like use the RegExp constructor with the source property to recrate the regex like in the example.

Note:

Because the 'g', always set lastIndex = 0 before using a regex with the exec method.

Example

/*
  Comments removal made easy.
  ...but please don't use this for ES6 template strings
*/
const _R = require('perf-regexes')

function removeComments(source) {
  const re = new RegExp([
    _R.JS_MLCOMM.source,
    _R.JS_SLCOMM.source,
    _R.JS_STRING.source,
    _R.JS_DIVISOR.source,
    _R.JS_REGEX.source].join('|'), 'gm');

  return source.replace(re, match => {
    return _R.ISCOMMENT.test(match) ? ' ' : match
  })
}

ES6 Template Strings

There's another regex to detect ES6 template strings but it is not recommended since there's no way to parse nested ES6 template strings with the limited regex engine of JavaScript.

This is an example of a complex, valid ES6 string:

let silly = `foo ${ "`" + '`' + `\`${ { bar }.baz }\`` }`

Known issues

JS_REGEXES fail matching literal regexes starting with // or />, please follow the best-practices and use /\/ or /\>.