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Asked: 2022-02-17 05:28:22 +0800 CST 2022-02-17 05:28:22 +0800 CST

Expression (regex) that takes 2 digits resembling month input

  • 772

What is needed is that the user enters the month in Number (without using any date controls); where you must validate that it is a positive number and that it accepts 1 to 9 and 0 to 2; only that they do not require month 01 or month 09 to be entered, if not 9 or 1; What I have done so far is this

^[+]?(0[1-9]|1[0-2])

The problem is that this must use the month 01 and that is what the user does not want.

var re = /^[+]?(0[1-9]|1[0-2])/;

console.log(re.test('') + ' No cumple' ); 
console.log(re.test('1')+ ' No cumple deberia Cumplir'); 
console.log(re.test('01'));
console.log(re.test('12'));
console.log(re.test('13') + ' No cumple');
console.log(re.test('9') + ' No cumple deberia Cumplir');

javascript

2 Answers

  1. Best Answer

    Test/^[+]?(0?[1-9]|1[0-2])$/

    I've made the zero optional 0?, and I've also made the string have to end there $.

    I don't know if this last condition works for you, but if I don't put it, it also accepts 13 (in reality it keeps 1, 3 doesn't pass the condition, but when passing part of the text string it considers it valid).

    If you do not put $, in fact, it will also give you valid: 22, 45, 023, etc.

    var re = /^[+]?(0?[1-9]|1[0-2])$/;

console.log(re.test('') + ' debería fallar' ); 
console.log(re.test('1') + ' debería cumplir'); 
console.log(re.test('01') + ' debería cumplir');
console.log(re.test('12') + ' debería cumplir');
console.log(re.test('13') + ' debería fallar');
console.log(re.test('9') + ' debería cumplir');

    • 3

  2. You could achieve it like this:

    • Add ?the 0(zero) in the group for months less than10
    • Append $to the end of the regular expression, to validate the entire string
    • OPTIONAL : take out [+]?( personally, I wouldn't know what this is for )

    demonstration:

    var re = /^(0?[1-9]|1[0-2])$/;

console.log(re.test('') + ' No cumple' ); 
console.log(re.test('1')+ ' No cumple deberia Cumplir'); 
console.log(re.test('01'));
console.log(re.test('12'));
console.log(re.test('13') + ' No cumple');
console.log(re.test('9') + ' No cumple deberia Cumplir');

    • 1