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Javascript – Regex result contains extra match/group with just a return

I would like to match everything between start and end given the following string:

const test = `this is the start
a
b
c
e
f
end
g
h
`;

I have the following regex

const output = test.match(/start((.|n)*)end/m);

No, output[0] contains the whole string that matched (with start and end)
output[1] is the match (everything between start and end)
output[2] is only a return (n)

DEMO

enter image description here

What I don’t understand is where does the second match/group (output2) come from. Amy suggestions?

Tags:

2

Answers


  1. 0

    This part of your regular expression: ((.|n)*) creates two capturing groups. The outer group collects all the matched "anything" characters matched by the inner * group. The inner group will contain the last matched single character.

    Note that you’d probably be better off with a slightly different regular expression to avoid the odd effect of collecting too many characters in the groups before backtracking takes over.

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  2. 0

    As Pointy mentioned, you have two capturing groups.

    If you use a named capturing group, this makes the code easier to write and understand:

    const test = `this is the start
a
b
c
e
f
end
g
h
`;

console.log(test.match(/start(?<between>(.|n)*)end/m).groups.between)
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