Regex for maximum 4 digit with dot, accept only number and separate with dot every thousand

Question

I have a problem to convert input in HTML to specific criteria :

I am able to achieve the last two with this :

value.replace(/\D/g, "").replace(/\B(?=(\d{3})+(?!\d))/g, ".");

How to add the first criteria ?

And seems like my regex is too long, a shorter one would be great.

user_11329890 · Answer

Remove all but first four digits:

const value = `123456`
console.log(
   value.replace(/\D/g, "").replace(/^(\d{4})\d+/, '$1').replace(/\B(?=(\d{3})+(?!\d))/g, ".")
)

user_11516951 · Answer

I would use a mask for the input,

("#id").inputmask({
                mask: "9.999", 
                placeholder: "",
                separator: "", 
               });

Then to check the value,

value.replace('.','');

and with a regular expression to verify that it is true that they are only digits and at most 4.

let regex_aux = /^\d{4}/;
 if(regex_aux.test(value)){
        //do something
    }