JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script>
<h4>1,3,9,6,5,7,12,32</h4>

        <input type="text" id="valueList"><button type="button" id="calculate">Calculate Stats</button>
        <br><br>
        <H2>Results</H2>
<ul id="results"><!--javascript will write items here--></ul>

JavaScript

$( "#calculate" ).click(processValues);

function processValues() {
	
	var valueSum = 0;
	var valueAverage = 0; 
	var valueMax = 0;
	var valueMin = Infinity; 
	
  //listens for click event
  $("#results" ).html( "" );//clears any list items from last calculation
  var valueString = $( "#valueList" ).val();
  var value = $.map(valueString.split(","), Number ); //this is an array
  valueCount = value.length; //get the lenght of the array (number of values)
  
	//
  //Use a loop (or loops) here to help calculate the sum, average, max, and min of the values
  //

// loop to find sum
for (var i=0; i <= valueCount; i++)
{
	if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
	{ 
		valueSum += +value[i];
	}
}

// praxis to find average
valueAverage = valueSum / valueCount;

// loop to find max
for (var i=0; i <=valueCount; i++)
{
		if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
		{
			if (value[i] > valueMax)
			{
				valueMax = value[i];
			}		
		}
}

//loop to find min
for (var i=0; i <=valueCount; i++)
{
		if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
		{
			if (value[i] <= valueMin)
			{
				valueMin = value[i];
			}		
		}
}

  $("#results" ).append( "<li>The values sum is : " + valueSum + ".</li>" );//appends values
	$("#results" ).append( "<li>The values average is : " + valueAverage + ".</li>" );//appends values
	$("#results" ).append( "<li>The values max is : " + valueMax + ".</li>" );//appends values	
	$("#results" ).append( "<li>The values min is : " + valueMin + ".</li>" );//appends values	
  $("#results" ).append( "<li>There are " + valueCount + " values.</li>" );//appends value count

  //need to append Sum, average, max, and min to bullet list here
  
  }