I'm trying to limit an input field to only numbers and the possibility of a "+" sign just at the string's [0] index. The idea is to let the user type their phone number, I have come up with this:
function main() {
let phone = document.getElementById('phone');
let phoneRegex = /[a-zA-Z]|[-!$%^&*()_|~=`{}[\]:";'<>?,./]/;
phone.value = phone.value.replace(phoneRegex, '');
console.log(phone.value);
}<input id="phone">
<button onclick="main()">Run</button>The thing is, this works fine, but I want to limit the first character to only a digit or a "+" sign, characters coming from index [1] and on should only be numbers.
I can't come up with an idea on how to solve this
Try this as a starting point (you'll probably want to expand it further to account for total string length, delimiters like -, etc.):
let phoneRegex = /\+?\d+/;
+ in a regular expression has a special meaning, so when we want to match the literal character "+" then we need to escape it. And following it with the ? character makes it optional:
\+?
Next, \d followed by + will match any sequence of one or more digits:
\d+
You can see a visualization of this pattern here.
I know I'm late in this game, but adding one more solution for me and other's future references.
I came up with this solution which works for me:
/^(\+|[0-9])?[0-9]{12}$/
Thanks
I want to limit the first character to only a digit or a "+" sign, characters coming from index [1] and on should only be numbers.
The regex:
/^\+?\d+$/
means:
From the beginning, one or zero + signs, then one or more numbers until the end.
Note the following regex symbols:
* - zero or more+ - one or more? - zero or one