RegEx to check first character as + and others are only numbers

Question

My use case is to validate a String only consists of + and the numbers. I have tried with so many regexes but couldn't able to fix my issue.

I have used /^[0-9]+$/ regex but it is failed in the 2 nd and 3rd(Obviously it is because it is having A Character) input.

My need is,

if the input is 00000094777216903 - TRUE
if the input is +947777216903     - TRUE (+ is fine if it is in the beginning of the string)
if the input is +947777216903A    - FALSE
if the input is 0000777216903A    - FALSE

Can anyone help me to achieve my need in JS.

And the problem is? Add an optional `+` before the number part — Andreas, Jan 13 '21 at 08:09
I am getting [Invalid regular expression: //^+[0-9]+$//: Nothing to repeat] error. — Hariprasath, Jan 13 '21 at 08:13
Of course you do, because `+` is a _quantifier_, and a quantifier with nothing _to_ quantify before it, makes no sense. That’s why you need to _escape_ the +, so that it is not taken as a quantifier any more, just as @melancia has shown - `\+` — CBroe, Jan 13 '21 at 08:16
If the `+` sign is optional, @Leonardum answer is what you're looking for. — emerson.marini, Jan 13 '21 at 08:19

WiatroBosy · Accepted Answer · 2021-01-13T08:19:29.750

1

Try this regex https://regex101.com/r/6wW84L/2

/(\+){0,1}[0-9]+$/

You have a working example below This /(+){0,1}[0-9]+$/ not //(+){0,1}[0-9]+$//

edited Jan 13 '21 at 08:19

answered Jan 13 '21 at 08:13

WiatroBosy

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Leonardum · Answer 2 · 2021-01-13T11:20:26.950

1

I believe this will do the trick:

/\+?[0-9]+/

Let me know if this does not, maybe I can adjust my answer.

Also, maybe this site will help you to find the exact RegEx you are looking for: https://www.regextester.com. I sure find it to be a handy tool!

edited Jan 13 '21 at 11:20

answered Jan 13 '21 at 08:17

Leonardum

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RegEx to check first character as + and others are only numbers

2 Answers2