在文本框中显示当前星期五的值

Question

i want user open webpage and textbox show value of current friday. i don't know how to use .val here is my code.

$(function() {
$("#dateInput").datepicker({

    //In Datepicker set the Calendar display start with Sunday (by default datepicker starts from Sunday)
    firstDay: 0,

    //Before Populating the Calendar set the Enabled & Disabled Dates using beforeShowDay(Date) function
    beforeShowDay: function (date) {

        //Get today's date
        var sunday = new Date();

        //Set the time of today's date to 00:00:00 
        sunday.setHours(0,0,0,0);

        sunday.setDate(sunday.getDate() - (sunday.getDay() || 0));

        //Set the Date to Sunday
        var saturday = new Date(sunday);
        var thrusday = new Date(sunday);
        var currentday = new Date();

        //0 is sunday 6 is saturday
        var currentdayofweek = currentday.getUTCDay();
        //console.log(currentday, "show currentday");
        //alert('value of currentday=>'+currentday);
        //alert('value of currentday of week=>'+currentdayofweek);
        //location.reload();

        //Now add 6 to Sunday to get the Date of Saturday (End of that Week)
        saturday.setDate(sunday.getDate() + 6);
        //add by kim
        thrusday.setDate(sunday.getDate() + 4);

        //edit by kim
        //return [(date >= thrusday && date <= saturday ), ''];
        // current day of week <5  mean user can select friday only day before friday
        return [(date > thrusday && date < saturday && currentdayofweek < 5), ''];
    }
});
  var temp = $("#dateInput").datepicker("option", "dateFormat", "yy-mm-dd");

  return temp;
});

and here is textbox code.

<input type="text" name="dateInput" id="dateInput"/>

1. i just want user can select only friday of current week in calendar
2. and value of friday in current week should show in text box before user select

Answer 1

This will fill the #dateInput input with the date corresponding to the Friday of the current week.

var date = new Date(),
    day = date.getDay(),
    dif = 5 - day >= 0 ? 5 - day : day - 5;
date.setTime( date.getTime() + (dif * 24 * 60 * 60 * 1000) );
$(document).ready(function() {
    $("#dateInput").val( date.getUTCFullYear() + "/" + (date.getMonth()+1) + "/" + date.getUTCDate() );
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input type="text" name="dateInput" id="dateInput"/>

</div>