RegEx Javascript - Only 0-2 spaces or hyphens in whole string?

user_8814843 0
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I have the following simple regex:
/^[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+$/

i would like to make it possible to have strings like "Blabla Bla bshfkhsf". But the whole string should not have more then 2 spaces or hyphens.

I know, that i can limit spaces with "\s{0,2}", but how do i place such limit in the regex, so that strings like above are possible and the limit applies to the whole string, not to a "single" character?

EDIT: May this be ok:

^[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+((\s)|(-))?[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+((\s)|(-))?[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+$

Is there any better way?

spaces limit javascript regex string
3 Answers

If you don't want to match spaces only, you can match the first part, then use the quantifier {0,2} to repeat the whole part again preceded by a character class [\s-] to match either a whitespace char or a hyphen.

If it should be a whitespace char only, you could use a mere \s (which could also match a newline)

Note that in your pattern, the whole alternation ((\s)|(-))? is optional so the minimum length of a single match would be 3 characters in that case. See this example.

You could update the pattern to

^[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+(?:[\s-][a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+){0,2}$

Explanation

  • ^ Start of string
  • [a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+ Match 1+ times any of the listed
  • (?: Non capture group
    • [\s-] Match either a whitspace char or -
    • [a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+ Match 1+ times any of the listed
  • ){0,2} Close the group and repeat it 0-2 times
  • $ End of string

See a regex demo

user_54249880

Instead of repeating the whole character class, you can just use lookahead to combine the conditions:

/^(?=[^\s-]*([\s-][^\s-]*){0,2}$)[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df\s-]+$/

Regex 101 demo. It's essentially two regexes in one:

(?=[^\s-]*([\s-][^\s-]*){0,2}$)

This part checks whether or not the whole string satisfies 'not more than 2 whitespace or - characters' rule.

[a-zA-Z\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df\s-]+$

This part checks whether or not the whole string satisfies 'only letters, whitespace and hyphens' rule. The point is, whole pattern matches only if both checks pass.

user_12290230

Parapharasing your requirement, you need to match a string that cannot have three or more spaces.

Use

/^(?!(?:\S*\s){3})[a-zA-Z\s\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+$/
  ^++++++++++++++^       ^^

So,

  1. \s is added to the expression so that it could match whitespace
  2. (?!(?:\S*\s){3}) ensures no three or more whitespace occurs in the string (there can be any non-whitespace characters in between thanks to \S*).

More things to consider

To disallow spaces at the start and end add more lookaheads

/^(?!\s)(?!.*\s$)(?!(?:\S*\s){3})[a-zA-Z\s\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+$/
  ^+++++++++++++^

To also disallow consecutive spaces

/^(?!\s)(?!.*\s$)(?!.*\s{2})(?!(?:\S*\s){3})[a-zA-Z\s\u00c4\u00e4\u00d6\u00f6\u00dc\u00fc\u00df]+$/
                 ^+++++++++^
user_113298900
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