How to auto format textbox inputs

Question

   Birthdate
      
   <         


        

Answer 1

I have an alternative that works with a jquery-ui datepicker, without formatter.js. It is intended to be called from the keyup and change events. It adds zero padding. It works with various supported date formats by constructing expressions from the dateFormat string. I can't think of a way to do it with fewer than three replaces.

// Example: mm/dd/yy or yy-mm-dd
var format = $(".ui-datepicker").datepicker("option", "dateFormat");

var match = new RegExp(format
    .replace(/(\w+)\W(\w+)\W(\w+)/, "^\\s*($1)\\W*($2)?\\W*($3)?([0-9]*).*")
    .replace(/mm|dd/g, "\\d{2}")
    .replace(/yy/g, "\\d{4}"));
var replace = "$1/$2/$3$4"
    .replace(/\//g, format.match(/\W/));

function doFormat(target)
{
    target.value = target.value
        .replace(/(^|\W)(?=\d\W)/g, "$10")   // padding
        .replace(match, replace)             // fields
        .replace(/(\W)+/g, "$1");            // remove repeats
}

https://jsfiddle.net/4msunL6k/