I'm doing some easy web application to practice my skill.
I'm using a regex to validate my phone input like this,
var reg = /^[\s()+-]*([0-9][\s()+-]*){6,20}$/;
if(!reg.test($('#input-phone').val())){
alert('error');
}
It works normally but it can't be empty. I don't know how to modify this to be able to reject empty field.
Check whether there is a value if so then use the regex
var reg = /^[\s()+-]*([0-9][\s()+-]*){6,20}$/;
var phone = $('#input-phone').val();
if (phone.length && !reg.test(phone)) {
alert('error');
}
The expression matches an empty string because all of its individual sequences are optional.
The easiest way of ensuring there is some data inside the expression is to add a lookahead for a single character at the start:
var reg = /^(?=.)[\s()+-]*([0-9][\s()+-]*){6,20}$/;
However, it may be easier still to explicitly test if the variable is empty before doing the regex test.