Regular Expressions 101

Positive Lookbehind(?<=var)

varthe literal text var (case sensitive)

Group 1(((\s+[\$\w]+[^\n{]*);)(\s+)var)

Group 2((\s+[\$\w]+[^\n{]*);)

Group 3(\s+[\$\w]+[^\n{]*)

\s+any whitespace character, repeated at least once

Character Class[\$\w]+

+matches at least one character from the set below:

\$the literal $ (36₁₀ / 44₈ / 24₁₆)

\wany word character

Negated Character Class[^\n{]*

*matches any number of characters outside the set below:

\na line-feed (newline) character (ASCII 10)

{the literal { (123₁₀ / 173₈ / 7B₁₆)

;the literal ; (59₁₀ / 73₈ / 3B₁₆)

Group 4(\s+)

\s+any whitespace character, repeated at least once

varthe literal text var (case sensitive)

Group 5(\s*)

\s*any whitespace character, repeated any number of times

Positive Lookahead(?=(?2))

(?2)calls group 2 as a subroutine

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?<=var)(((\s+[\$\w]+[^\n{]*);)(\s+)var)(\s*)(?=(?2))

New

{
  var $jqueryFoo = 'foo';
  var bar        = 'bar';
}

{
  var foo    = require('/foo');
  var bar    = require('/bar');
  var foobar = require('/foobar');
}

{
  var foo = 'foo';
  var bar = 'bar';

  var baz;
}

{
  var foo = 'foo';
  var bar = 'bar';

  BAZ = 'baz';
}

{
  var foo = 'foo';
  var bar = 'bar';
  var obj = {
    foo: 'foo',
    bar: 'bar'
  };
}

Substitution

\3,\4