JavaScript Input

HTML

Identify the HTML for a grade calculator; it enables input and totals.

DIV element defines a division or a section in an HTML document. Used to divide headings, totals, and input in this example.
SPAN element defines a inline container within text. Used to capture different totals in this example.
INPUT tag specifies an input field where the user can enter data. Used to capture series of numbers in this example.
ID attributes are used by CSS for style and JavaScript for reference. Used to update totals in this example.

Resources HTML

JavaScript newInputLine

Identify the function that generates a new input line after each score is entered.

Resources createElement

JavaScript calculator

Indentify the code below calculates the the total, count, and average of the user inputs.

Resources getElements

HTML Magic runs Calculator

The code below runs in VSCode and on Jupyter Notebook.

SCRIPT tag is used to embed JavaScript inside of HTML

Hacks

Here are some ideas to alter this calculator.

Input two scores: 1.8 out of 2
Add title: Tool Check 1.8 out of 2
Format with colors or put into a table
Advanced, save in localstorage and repaint on load

Sample Table

Assignment	Score	Maximum
Tool Check	1.8	2.0
Lab Notebook Check	1.7	2.0
Pair Showcase	4.7	5.0

Here are some ideas to alter former calculator runtime, source.

Right justify result
Test conditions on small, big, and decimal numbers, report on findings. Fix issues.
Add the common math operation that is missing from calculator (/)
Advanced, implement a 1 number operation (ie SQRT)

Grade Calculator

%%html

<!-- Help Message -->
<h3>Input scores, press tab to add each new number.</h3>
<!-- Totals -->
<ul>
<li>
    Total : <span id="total">0.0</span>
    Count : <span id="count">0.0</span>
    Average : <span id="average">0.0</span>
</li>
</ul>
<!-- Rows added using scores ID -->
<div id="scores">
    <!-- javascript generated inputs -->
</div>

<script>
// Executes on input event and calculates totals
function calculator(event) {
    var key = event.key;
    // Check if the pressed key is the "Tab" key (key code 9) or "Enter" key (key code 13)
    if (key === "Tab" || key === "Enter") { 
        event.preventDefault(); // Prevent default behavior (tabbing to the next element)
   
        var array = document.getElementsByName('score'); // setup array of scores
        var total = 0;  // running total
        var count = 0;  // count of input elements with valid values

        for (var i = 0; i < array.length; i++) {  // iterate through array
            var value = array[i].value;
            if (parseFloat(value)) {
                var parsedValue = parseFloat(value);
                total += parsedValue;  // add to running total
                count++;
            }
        }

        // update totals
        document.getElementById('total').innerHTML = total.toFixed(2); // show two decimals
        document.getElementById('count').innerHTML = count;

        if (count > 0) {
            document.getElementById('average').innerHTML = (total / count).toFixed(2);
        } else {
            document.getElementById('average').innerHTML = "0.0";
        }

        // adds newInputLine, only if all array values satisfy parseFloat 
        if (count === document.getElementsByName('score').length) {
            newInputLine(count); // make a new input line
        }
    }
}

// Creates a new input box
function newInputLine(index) {

    // Add a label for each score element
    var title = document.createElement('label');
    title.htmlFor = index;
    title.innerHTML = index + ". ";    
    document.getElementById("scores").appendChild(title); // add to HTML

    // Setup score element and attributes
    var score = document.createElement("input"); // input element
    score.id =  index;  // id of input element
    score.onkeydown = calculator // Each key triggers event (using function as a value)
    score.type = "number"; // Use text type to allow typing multiple characters
    score.name = "score";  // name is used to group all "score" elements (array)
    score.style.textAlign = "right";
    score.style.width = "5em";
    document.getElementById("scores").appendChild(score);  // add to HTML

    // Create and add blank line after input box
    var br = document.createElement("br");  // line break element
    document.getElementById("scores").appendChild(br); // add to HTML

    // Set focus on the new input line
    document.getElementById(index).focus();
}

// Creates 1st input box on Window load
newInputLine(0);

</script>

Input scores, press tab to add each new number.

Total : 0.0 Count : 0.0 Average : 0.0