Printing html

File: printing_html.html (click for a live demo)
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="utf-8">
	<title>math.js | printing HTML</title>

	<script src="https://unpkg.com/mathjs@14.0.1/lib/browser/math.js"></script>

	<style>
		body {
			font-size: 11pt;
			font-family: verdana, arial, sans-serif;
		}

		h1 {
			font-size: 1rem;
		}

		fieldset {
			display: inline;
			margin: 0 50px 10px 0;
			padding: 0;
			border: none;
		}

		input[type=text] {
			font-size: 11pt;
			font-family: verdana, arial, sans-serif;
			padding: 5px;
			width: calc(100% - 14px);
		}

		label {
			margin: 0 5px 0 0;
		}

		table {
			width: 100%;
			border-collapse: collapse;
		}

		table td,
		table th {
			padding: 5px;
			border: 1px solid LightGrey;
		}

		table th {
			background-color: LightGrey;
		}

		/* style the HTML output */
		.math-function {
			color: Purple;
			font-weight: bold;
		}

		.math-number {
			color: Blue;
		}

		.math-boolean {
			color: Green;
		}

		.math-string {
			color: Grey;
		}

		.math-string::before,
		.math-string::after {
			content: "\"";
		}

		.math-property {
			font-style: italic;
		}

		.math-explicit-binary-operator::before,
		.math-explicit-binary-operator::after {
			content: " ";
		}

		.math-separator::after,
		.math-assignment-operator::after {
			content: " ";
		}
	</style>
</head>
<body>
<h1>Expression evaluation and HTML code generation with math.js</h1>
<form>
	<fieldset>
		Parenthesis option:
		<label><input type="radio" name="parenthesis" value="keep" checked>keep</label>
		<label><input type="radio" name="parenthesis" value="auto">auto</label>
		<label><input type="radio" name="parenthesis" value="all">all</label>
	</fieldset>
	<fieldset>
		Implicit multiplication:
		<label><input type="radio" name="implicit" value="hide" checked>hide</label>
		<label><input type="radio" name="implicit" value="show">show</label>
	</fieldset>
</form>
<table>
	<tr>
		<th>Expression</th>
		<td><input type="text" id="expr"/></td>
	</tr>
	<tr>
		<th>Result</th>
		<td><div id="result"></div></td>
	</tr>
	<tr>
		<th>HTML output</th>
		<td><div id="output">$$$$</div></td>
	</tr>
	<tr>
		<th>HTML code</th>
		<td><div id="code">$$$$</div></td>
	</tr>
</table>
<script>
  const expr = document.getElementById('expr')
  const output = document.getElementById('output')
  const code = document.getElementById('code')
  const result = document.getElementById('result')
  let options = {parenthesis: 'keep', implicit: 'hide'}

  // initialize with an example expression
  expr.value = 'sqrt(75/3)+det([[-1,2],[3,1]])-sin(pi/4)^2'

  function print () {
    let parsed = null

    try {
      // parse the expression
      parsed = math.parse(expr.value)

      // evaluate the result of the expression
      result.innerHTML = math.format(parsed.compile().evaluate())

      // print the HTML output
      const html = math.parse(expr.value).toHTML(options)
      output.innerHTML = html

      // print the HTML code
      code.innerHTML = html.replace(/</g, '&lt;').
      replace(/>/g, '&gt;').
      replace(/&lt;\/span&gt;/g, '&lt;/span&gt;<br />')
    }
    catch (err) {
      result.innerHTML = '<span style="color: red;">' + err.toString() + '</span>'
    }
  }

  window.onload = print
  expr.oninput = print

  // make the controls work
  const controls = document.querySelectorAll('input[type=radio]')
  controls.forEach(function (control) {
    control.onclick = function() {
      options[control.name] = control.value
      print()
    }
  })
</script>
</body>
</html>