translating RegEx syntax working in php and python to JS

Question

I have this RegEx syntax: "(?<=[a-z])-(?=[a-z])"

It captures a dash between 2 lowercase letters. In example below the second dash is captured:

Krynica-Zdrój, ul. Uzdro-jowa

Unfortunately I can't use <= in JS. My ultimate goal is to remove the hyphen with RegEx replace.

About /\b-\b/g, it returns both hyphens. About the second pattern, I have no idea how to get it to work, without changes it doesn't detect anything. — Ryszard Jędraszyk
– Ryszard Jędraszyk, Commented Sep 22, 2016 at 13:16
Yes, I provided a solution below. Let me delete my first comment. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Sep 22, 2016 at 13:16

Wiktor Stribiżew · Accepted Answer · 2016-09-22 13:41:36Z

1

It seems to me you need to remove the hyphen in between lowercase letters.

Use

var s = "Krynica-Zdrój, ul. Uzdro-jowa";
var res = s.replace(/([a-z])-(?=[a-z])/g, "$1");
console.log(res);

Note the first lookbehind is turned into a simple capturing group and the second lookahead is OK to use since - potentially, if there are chunks of hyphenated single lowercase letters - it will be able to deal with overlapping matches.

Details:

([a-z]) - Group 1 capturing a lowercase ASCII letter
- - a hyphen
(?=[a-z]) - that is followed with a lowercase ASCII letter that is not added to the result -/g - a global modifier, search for all occurrences of the pattern
"$1" - the replacement pattern containing just the backreference to the value stored in Group 1 buffer.

VBA sample code:

Sub RemoveExtraHyphens()
Dim s As String
Dim reg As New regexp

reg.pattern = "([a-z])-(?=[a-z])"
reg.Global = True

s = "Krynica-Zdroj, ul. Uzdro-jowa"
Debug.Print reg.Replace(s, "$1")
End Sub

edited Sep 22, 2016 at 13:41

answered Sep 22, 2016 at 12:59

Wiktor Stribiżew

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4 Comments

Ryszard Jędraszyk Over a year ago

I have tried /([a-z])-(?=[a-z])/g and it returns "o-" in my example.

Wiktor Stribiżew Over a year ago

Where is your example? Please share. If you use mine, you will see it works well.

Ryszard Jędraszyk Over a year ago

My example is Krynica-Zdrój, ul. Uzdro-jowa, I have checked /([a-z])-(?=[a-z])/g on regex101.com/#javascript, I also maybe don't understand something, so I'll explain that I need the pattern to be used in VBA which uses JS RegEx syntax.

Ryszard Jędraszyk Over a year ago

Thank You, now everything is clear to me and works perfectly, just replaced Dim reg As New regexp with Dim reg As Object Set reg = CreateObject("vbscript.regexp"), because I was getting error, probably had no reference to regexp.

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