regexpu-core
regexpu is a source code transpiler that enables the use of ES2015 Unicode regular expressions in JavaScript-of-today (ES5).
regexpu-core contains regexpu’s core functionality, i.e. rewritePattern(pattern, flag)
, which enables rewriting regular expressions that make use of the ES2015 u
flag into equivalent ES5-compatible regular expression patterns.
Installation
To use regexpu-core programmatically, install it as a dependency via npm:
Then, require
it:
API
This module exports a single function named rewritePattern
.
rewritePattern(pattern, flags, options)
rewritePattern(pattern, flags, options)
This function takes a string that represents a regular expression pattern as well as a string representing its flags, and returns an ES5-compatible version of the pattern.
regexpu-core can rewrite non-ES6 regular expressions too, which is useful to demonstrate how their behavior changes once the u
and i
flags are added:
The optional options
argument recognizes the following properties:
dotAllFlag
(default: false
)
dotAllFlag
(default: false
)Setting this option to true
enables support for the s
(dotAll
) flag.
unicodePropertyEscape
(default: false
)
unicodePropertyEscape
(default: false
)Setting this option to true
enables support for Unicode property escapes:
lookbehind
(default: false
)
lookbehind
(default: false
)Setting this option to true
enables support for lookbehind assertions.
namedGroup
(default: false
)
namedGroup
(default: false
)Setting this option to true
enables support for named capture groups.
onNamedGroup
onNamedGroup
This option is a function that gets called when a named capture group is found. It receives two parameters: the name of the group, and its index.
useUnicodeFlag
(default: false
)
useUnicodeFlag
(default: false
)Setting this option to true
enables the use of Unicode code point escapes of the form \u{…}
. Note that in regular expressions, such escape sequences only work correctly when the ES2015 u
flag is set. Enabling this setting often results in more compact output, although there are cases (such as \p{Lu}
) where it actually increases the output size.
Author
License
regexpu-core is available under the MIT license.
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