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HTML Attributes

Intermediate

HTML Boolean Attributes

Learn disabled, checked, selected, readonly, multiple, autofocus as part of the HTML attribute system: what they configure, where they belong and which mistakes to avoid.

Boolean

Boolean attributes are true when they are present.

Boolean attributes work differently from normal name-value attributes. If the attribute is present, the setting is true. If it is missing, the setting is false.

Writing disabled="false" does not make a control enabled. The attribute is still present, so it is still disabled.

Attribute group: disabled, checked, selected, readonly, multiple, autofocus. Attributes where presence means true and absence means false.

What belongs here

Learn attributes by purpose, not by memorizing random names.

disabled

Prevents interaction and usually prevents submission.

checked

Marks a checkbox or radio as selected by default.

selected

Marks an option as selected by default.

readonly

Allows reading/copying but not editing.

multiple

Allows multiple values for certain controls.

autofocus

Requests initial focus when the page loads.

Syntax in context

Presence is the value.

Write boolean attributes without a value, or with the same name as value if you must. Do not write false.

<input type="checkbox" name="terms" checked>
<input type="email" name="email" readonly value="student@example.com">
<button type="submit" disabled>Send later</button>

Good versus weak

Small attribute choices can change behavior, accessibility and security.

Good

<input type="checkbox" name="terms" checked>
<input type="email" name="email" readonly value="student@example.com">
<button type="submit" disabled>Send later</button>

Weak

<button disabled="false">This is still disabled</button>
<input checked="no" type="checkbox">

HTML quick reference

Reusable examples for quick reference.

Use these patterns when you need the syntax quickly. Each example has its own anchor, so search engines and readers can land directly on the exact pattern instead of only at the top of the lesson.

Semantic pattern

HTML pattern 1

A clean version of the markup from this lesson. Use it when you need the correct HTML shape quickly.

<input type="checkbox" name="terms" checked>
<input type="email" name="email" readonly value="student@example.com">
<button type="submit" disabled>Send later</button>
What this gives you

Meaningful markup that stays understandable before CSS and JavaScript are added.

Editable lab starter

HTML pattern 2

The starting point from the practice lab. Change the HTML first, then use CSS only for presentation.

<main class="demo-card">
  <form>
    <label><input type="checkbox" checked> I want updates</label>
    <input type="text" value="Readonly value" readonly>
    <button type="submit" disabled>Submit disabled</button>
  </form>
</main>

<style>
* { box-sizing: border-box; }
body {
  min-height: 100vh;
  margin: 0;
  display: grid;
  place-content: center;
  padding: 24px;
  font-family: system-ui, sans-serif;
  background: #07111f;
  color: #ffffff;
}

.demo-card {
  width: min(760px, calc(100vw - 48px));
  border-radius: 24px;
  padding: 28px;
  background: rgba(8, 12, 20, 0.94);
  border: 1px solid rgba(140, 255, 193, 0.26);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.32);
}

.content-panel {
  margin-top: 18px;
  border-radius: 18px;
  padding: 18px;
  background: rgba(255, 255, 255, 0.06);
}

.muted-card { color: #b8c4d6; }
.label, caption {
  color: #8cffc1;
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1, h2, strong { color: #8cffc1; }
p, li, dd, figcaption { color: #d6deec; line-height: 1.65; }
a { color: #62d5ff; font-weight: 800; }
img, iframe, video, svg { max-width: 100%; border-radius: 18px; }
iframe { width: 100%; min-height: 180px; border: 1px solid rgba(255,255,255,0.16); }

label { display: block; margin-top: 14px; color: #d6deec; font-weight: 800; }
input, button {
  display: block;
  width: 100%;
  margin-top: 8px;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  padding: 12px 14px;
  font: inherit;
}

button {
  margin-top: 16px;
  border: 0;
  background: #8cffc1;
  color: #07111f;
  font-weight: 900;
  cursor: pointer;
}

button:disabled { opacity: 0.56; cursor: not-allowed; }
table { width: 100%; border-collapse: collapse; }
th, td { border: 1px solid rgba(255, 255, 255, 0.16); padding: 12px 14px; }
</style>
What this gives you

A complete practice snippet that shows how the HTML behaves in context.

Pattern to avoid

HTML pattern 3

A weak pattern from the lesson. Use it as a warning sign when reviewing real pages.

<button disabled="false">This is still disabled</button>
<input checked="no" type="checkbox">
What this gives you

A recognizable mistake you can search for and refactor.

Rules that matter

Use these rules before publishing real HTML.

Do not write false

Boolean attributes do not become false because the string says false.

Remove the attribute

To turn the state off, remove the attribute from the element.

Disabled fields may not submit

Do not disable a field if the server still needs its value.

Use autofocus carefully

Automatic focus can be annoying and disorienting.

Production thinking

Attributes are tiny pieces of HTML with real product impact.

Why does this matter?

Attributes are small, but they change how an element works. A good attribute can make a link usable, an image understandable, a form easier to complete or a script safer to load.

Accessibility

Disabled and readonly controls should be visually and semantically clear so users understand what can be changed.

Production note

Boolean attributes often represent interface state. JavaScript should add and remove them intentionally.

Live code lab

Change the code and run the example.

Edit the HTML or CSS, then use Run to refresh the preview. The preview is isolated, so links and forms stay inside this practice area.

Mini assignment

Try this now.

  • Change one tag, attribute or text value in the example.
  • Run the preview and describe exactly what changed.
  • Reset the lab and repeat the same change without looking at the original.

Practice assignment

Do this before moving to the next lesson.

  1. Change one meaningful part of the HTML, not only the visible text.
  2. Run the preview and check whether the result still makes semantic sense.
  3. Explain why the element or attribute you changed belongs in this exact place.

Try it yourself

Boolean attributes as state

Live preview

Self-check

Before you continue, prove that you own this lesson.

Intermediate

Do not only read this page. Answer these questions out loud or write the answers in your own notes. If one answer feels vague, revisit the examples before moving on.

  1. Can you explain what problem this lesson solves in a real website?
  2. Can you identify the most important tag or attribute from this lesson?
  3. Can you name one accessibility mistake this lesson helps prevent?
  4. Can you write one good example and one weak example without copying the page?
  5. Can you explain when you would use this in production and when you would avoid it?