JSFiddle - React, Tailwind, and code Playground

by Nicolaus Maloney

HTML

Year: <input type='text' id='year' 
  maxlength='4' style='width: 4em' value='2000'/>
&#160;&#160;
Month: <select id='month'>
  <option value='jan'>January</option>
  <option value='feb'>February</option>
  <option value='mar'>March</option>
  <option value='apr'>April</option>
  <option value='may'>May</option>
  <option value='jun'>June</option>
  <option value='jul'>July</option>
  <option value='aug'>August</option>
  <option value='sep'>September</option>
  <option value='oct'>October</option>
  <option value='nov'>November</option>
  <option value='dec'>December</option>
</select>&#160;&#160;
Day of month: <input type='text' id='day' 
  maxlength='2' style='width: 2em' value='1'/>

<p><button id='compute'>Compute!</button></p>
<div id='answer'></div>

JavaScript

// Fix this function so that it computes the
// correct day of the week.

function dayOfWeek(year, month, day) {
  const y = year - 2000;
  const ly = Math.floor(y / 4);
  const monNum = month;
  const dom = day;
//  const lyAdj = if ()
  
  return "Monday";
}



function elem(id) {
  return document.getElementById(id);
}
function fieldVal(id) {
  return elem(id).value;
}
function activate() {
  const year = fieldVal('year');
  const month = fieldVal('month');
  const day = fieldVal('day');
  elem('answer').innerHTML = 
    dayOfWeek(year, month, day);
}
elem('compute')
  .addEventListener('click', activate);