Regex expression that matches if the string contain only spaces?

Question

I am using formik with yup to validate a form. In one input it passes if it contains only spaces, which is not valid for my use-case. So I went through Google to find some kind of regex so if the string only has spaces it would throw some message, but I didn't find anything.

nome: string()
      .min(3, '* Deve conter no mínimo 3 caracteres')
      .required('* Este campo é obrigatório')
      .matches(/[^\s*].*[^\s*]/g, '* This field cannot contain only blankspaces'),

The problem with this is that when it reaches 3 characters even with required yup condition the validation doesn't work, and matches with regex don't block the spaces. So far I managed a work-around with: nome: values.nome.trim().replace(/\s+/g, ' ') But with the correct regex expression I can throw the error in real time.

Try /^\S+$/ if you need to match a whole string that has no whitespace — Wiktor Stribiżew
– Wiktor Stribiżew, Commented May 13, 2020 at 17:42
Some kinda of : space.next === someCaracter ? valid : notValid logic and this "space next" would be looked by some regex express — cristiano soares
– cristiano soares, Commented May 13, 2020 at 17:42
Are you just making sure that the field does not contany any white space? In this case why not simply matchin for \s+ ? — Pitto
– Pitto, Commented May 13, 2020 at 17:43
@WiktorStribiżew it worked if the whole string has no whitespace but if I wanna some kinda of example: fullname= Alex martines ? — cristiano soares
– cristiano soares, Commented May 13, 2020 at 18:05

Wiktor Stribiżew · Accepted Answer · 2021-04-24 10:38:47Z

10

You may use

/^(?!\s+$).*/
/^(?!\s+$)/
/^\s*\S.*$/
/^\s*\S[^]*$/
/^\s*\S[\s\S]*$/

The first two regexps will match any string that is not equal to 1 or more whitespaces.

The last third, fourth and fifth match a string that contains at least one non-whitespace char.

See the regex demo

Details

^ - start of string
(?!\s+$) - a negative lookahead that fails the match if there are 1 or more whitespaces and end of string immediately to the right of the current location
.* - 0 or more chars other than line break chars, as many as possible
\s*\S.* - zero or more whitespaces, a non-whitespace, and then any zero or more chars other than line break chars
\s*\S[^]* / \s*\S[\s\S]* - same as above but any chars including line breaks can appear after the non-whitespace char
$ - end of string

edited Apr 24, 2021 at 10:38

answered May 13, 2020 at 18:27

Wiktor Stribiżew

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1 Comment

cristiano soares Over a year ago

Thanks a lot! Perfect answer

Pitto · Accepted Answer · 2022-03-23 20:58:33Z

3

Since you want to match in case any white space is present please try:

nome: string()
      .min(3, '* Deve conter no mínimo 3 caracteres')
      .required('* Este campo é obrigatório')
      .matches(/^(\S+$)/g, '* This field cannot contain only blankspaces'),

edited Mar 23, 2022 at 20:58

answered May 13, 2020 at 17:44

Pitto

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3 Comments

cristiano soares Over a year ago

Sorry, i mistook the error message, if the field has only white spaces then its not valid

cristiano soares Over a year ago

.matches(/^(\S+$)/, '* This field cannot contain only blankspaces') This worked for me, thanks!

Pitto Over a year ago

I am glad it worked for you :) Please don't forget to upvote the answer and / or choose it as final answer.

muswain · Accepted Answer · 2022-01-07 02:41:24Z

1

.matches(/^(\S+$)/, '* This field cannot contain only blankspaces') worked for me as well.

Mark the capital S but not the small s

edited Jan 7, 2022 at 2:41

answered Nov 11, 2021 at 22:32

muswain

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