regex in javascript strings: remove numeric or alphabetic characters

Built into Javascript’s String primitive are Regex methods such as .match and .replace.¹

We can use the latter to sanitize inputs. A simply way to clean a phone number, for example is phoneNumber.replace(/[^0-9]/g, "").

As you can see in this RegexPal², the non-numbers are highlighted:

To use this in a function, it’s as simple as:

const phone = "+1 (123) 456-9800"
console.log(phone.replace(/[^0-9]/g, "")) // 11234569800

To replace alphabetic characters, we would modify the pattern. For example /[^A-z]/g would be all upper and lower case characters.

Footnotes

• ¹ String.prototype.replace() | MDN
• ² Finding non-numeric inputs | Regex Pal