I am trying to remove illegal characters from a user input on a browser input field.
const myInput = '46432e66Sc'
var myPattern = new RegExp(/^[a-z][a-z0-9]*/);
var test = myPattern.test(myInput);
if (test === true) {
console.log('success',myInput)
} else {
console.log("fail",myInput.replace(???, ""))
}
I can test with the right regex and it works just fine. Now I am trying to remove the illegal characters. The rules are, only lower case alpha character in the first position. All remaining positions can only have lower case alpha and numbers 0-9. No spaces or special characters. I am not sure what pattern to use on the replace line.
Thanks for any help you can provide.
Brad
You could try the below code:
const myInput = '46432e66Sc'
var myPattern = new RegExp(/^[a-z][a-z0-9]*/);
var test = myPattern.test(myInput);
if (test === true) {
console.log('success',myInput)
} else {
console.log("fail",myInput.replace(/[^a-z0-9]/g, ""))
}
Replace is using the following regexp: /[^a-z0-9]/g. This matches all characters that are not lowercase or numeric.
You can validate your regexp and get help from cheatsheet on the following page: https://regexr.com/
You could handle this by first stripping off any leading characters which would cause the input to fail. Then do a second cleanup on the remaining characters:
var inputs = ['abc123', '46432e66Sc'];
inputs.forEach(i => console.log(i + " => " + i.replace(/^[^a-z]+/, "")
.replace(/[^a-z0-9]+/g, "")));Note that after we have stripped off as many characters as necessary for the input to start with a lowercase, the replacement to remove non lowercase/non digits won't affect that first character, so we can just do a blanket replacement on the entire string.