JavaScript date object from <input type=date>

Question

I'm trying to create a javascript date object in the focus.add_days function to add some days to the given date in a element. the problem is that the javascript object doesn't expect a string "Y-m-d" so how can I create the date object without parsing the string "Y-m-d" into pieces, or is the only way?

trigger = {
fecha_ini: function(){
    $('input[name="fecha_ini"]').on('change',function(){
      console.log('hi');
      var fecha_fin = $(':input [name=fecha_fin]');
      var min = $(this).val();
      //here is where i pass the "Y-m-d" string as the date argument
      var max = fechas.add_days(min,31*4);
      fecha_fin.attr('min',min);
      fecha_fin.attr('max',max);
      fecha_fin.val('');
    })
  }
};

fechas = {
  add_days: function addDays(date, days) {
    //here is where i use the string "Y-m-d" to create the date object, but obviusly doesnt work
    var result = new Date(date);
    result.setDate(date.getDate() + days);
    return result;
}
};

trigger.fecha_ini();

Answer 1

Use valueAsDate:

valueAsDate
Returns: Date

Returns / Sets the value of the element, interpreted as a date, or null if conversion is not possible.

Demo:

<input type="date" id="d" value="2018-02-14">

<button onclick="console.log( document.getElementById('d').valueAsDate )">
change the date (or not) and click me
</button>

Answer 2

how can I create the date object without parsing the string "Y-m-d" into pieces, or is the only way?

While Date.parse will convert strings in y/m/d/ format to date objects, manual parsing is the only sensible way:

// s is format y-m-d
// Returns a date object for 00:00:00 local time
// on the specified date
function parseDate(s) {
  var b = s.split(/\D/);
  return new Date(b[0], --b[1], b[2]);
}

ES5 specifies a form of ISO 8601 that should be supported by all browsers, however it is not supported consistently or by all browsers in use.