Query on regexp using JavaScript

Question

I am working on regexp where if the user enter consecutive spaces, dashes, apostrophes then I have to show one error message

^[a-zA-Z0-9!@#\$%\^\&*\)\(+=._-]{0,}$

With the above reg exp I am getting if the user enter one dashes I am getting error but here I want spaces apostrophes.

Do you want something like ^(?!.*( {2}|--|''))[a-zA-Z0-9!@#\$%\^\&*\)\(+=._ '-]*$? — logi-kal
– logi-kal, Commented Jun 24, 2017 at 18:53
thanks for the answer i want only for consecutive spaces,-----' not for letter — Mr.M
– Mr.M, Commented Jun 24, 2017 at 19:15

Bamieh · Accepted Answer · 2017-06-24 18:55:40Z

1

If I understood correctly, basically you have to do Back-referencing in order to check for double words (or more than doubles)

/(\s-,)\1+/.test(...)

const hasDoubles = new RegExp(/(\s|-|,)\1+/);

console.log( hasDoubles.test("hello - ") ) // false
console.log( hasDoubles.test("--") ) // true
console.log( hasDoubles.test("  ") ) // true
console.log( hasDoubles.test(",,") ) // true

This code captures any space \s or dashes - or , then checks if it occurs again 1 or more times denoted by \1+ the \1 for back-referencing the capture group, and + for 1 or more occurances.

answered Jun 24, 2017 at 18:55

Bamieh

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6 Comments

Mr.M Over a year ago

thanks for the quick answer but when i try in regex online i am not getting the result let say for exmple if i am typing consecutive ----- or spaces or """""""

Bamieh Over a year ago

can you send me a link? because i tried an online solution and all the consecutive cases match(or the console). ------- does match it all for example.

Bamieh Over a year ago

youre missing a ( in the beginning, here a working link regex101.com/r/F0bK6X/3

Bamieh Over a year ago

also you didnt mention quotes, you said apostrophes. anyways, here is another link with double quotes check, you can add whatever you want if you got the pattern regex101.com/r/F0bK6X/4

Mr.M Over a year ago

Thanks for your help but this was not considering space how to include space for this

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