Number Input

Code

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: Inter, system-ui, sans-serif;
  background: #050910;
  color: #f2f6ff;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.demo {
  width: 100%;
  max-width: 480px;
}
.demo-title {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 0.375rem;
}
.demo-sub {
  color: #475569;
  font-size: 0.875rem;
  margin-bottom: 2rem;
}

.section {
  margin-bottom: 1.75rem;
}
.section-label {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #475569;
  margin-bottom: 0.625rem;
}

/* ── Number Input ── */
.num-input {
  display: inline-flex;
  align-items: center;
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 10px;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.04);
  transition: border-color 0.2s;
}
.num-input:focus-within {
  border-color: rgba(99, 179, 237, 0.5);
  box-shadow: 0 0 0 3px rgba(99, 179, 237, 0.12);
}

.num-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.75rem;
  background: rgba(255, 255, 255, 0.05);
  border: none;
  color: #94a3b8;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  flex-shrink: 0;
  user-select: none;
}
.num-btn:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.1);
  color: #f2f6ff;
}
.num-btn:active:not(:disabled) {
  background: rgba(255, 255, 255, 0.15);
}
.num-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}
.num-btn--dec {
  border-right: 1px solid rgba(255, 255, 255, 0.08);
}
.num-btn--inc {
  border-left: 1px solid rgba(255, 255, 255, 0.08);
}

.num-field {
  width: 5rem;
  height: 2.75rem;
  background: transparent;
  border: none;
  color: #f2f6ff;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  text-align: center;
  outline: none;
  padding: 0;
  -moz-appearance: textfield;
}
.num-field::-webkit-outer-spin-button,
.num-field::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

/* ── Disabled state ── */
.num-input--disabled {
  opacity: 0.45;
  cursor: not-allowed;
}
.num-input--disabled .num-field {
  cursor: not-allowed;
}

document.querySelectorAll(".num-input:not(.num-input--disabled)").forEach(function (widget) {
  var min = widget.dataset.min !== undefined ? parseFloat(widget.dataset.min) : -Infinity;
  var max = widget.dataset.max !== undefined ? parseFloat(widget.dataset.max) : Infinity;
  var step = widget.dataset.step !== undefined ? parseFloat(widget.dataset.step) : 1;

  var field = widget.querySelector(".num-field");
  var dec = widget.querySelector(".num-btn--dec");
  var inc = widget.querySelector(".num-btn--inc");

  function parse(v) {
    var n = parseFloat(v);
    return isNaN(n) ? 0 : n;
  }

  function round(n) {
    // round to step precision to avoid floating-point drift
    var decimals = (step.toString().split(".")[1] || "").length;
    return parseFloat(n.toFixed(decimals));
  }

  function clamp(n) {
    return Math.min(Math.max(n, min), max);
  }

  function set(n) {
    var clamped = clamp(round(n));
    field.value = clamped;
    dec.disabled = clamped <= min;
    inc.disabled = clamped >= max;
  }

  dec.addEventListener("click", function () {
    set(parse(field.value) - step);
  });
  inc.addEventListener("click", function () {
    set(parse(field.value) + step);
  });

  field.addEventListener("change", function () {
    set(parse(field.value));
  });

  field.addEventListener("keydown", function (e) {
    if (e.key === "ArrowUp") {
      e.preventDefault();
      set(parse(field.value) + step);
    }
    if (e.key === "ArrowDown") {
      e.preventDefault();
      set(parse(field.value) - step);
    }
  });

  // initialise boundary state
  set(parse(field.value));
});

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Number Input</title>
  <link rel="stylesheet" href="style.css" />
</head>
<body>
  <div class="demo">
    <h1 class="demo-title">Number Input</h1>
    <p class="demo-sub">Stepper input with min/max/step support and keyboard navigation.</p>

    <section class="section">
      <p class="section-label">Default</p>
      <div class="num-input" data-step="1">
        <button class="num-btn num-btn--dec" aria-label="Decrement">−</button>
        <input class="num-field" type="text" inputmode="numeric" value="0" aria-label="Number value" />
        <button class="num-btn num-btn--inc" aria-label="Increment">+</button>
      </div>
    </section>

    <section class="section">
      <p class="section-label">With min (0) and max (10)</p>
      <div class="num-input" data-min="0" data-max="10" data-step="1">
        <button class="num-btn num-btn--dec" aria-label="Decrement" disabled>−</button>
        <input class="num-field" type="text" inputmode="numeric" value="0" aria-label="Number value, 0 to 10" />
        <button class="num-btn num-btn--inc" aria-label="Increment">+</button>
      </div>
    </section>

    <section class="section">
      <p class="section-label">Step 0.5, min −5, max 5</p>
      <div class="num-input" data-min="-5" data-max="5" data-step="0.5">
        <button class="num-btn num-btn--dec" aria-label="Decrement">−</button>
        <input class="num-field" type="text" inputmode="decimal" value="0" aria-label="Number value, −5 to 5" />
        <button class="num-btn num-btn--inc" aria-label="Increment">+</button>
      </div>
    </section>

    <section class="section">
      <p class="section-label">Disabled</p>
      <div class="num-input num-input--disabled" data-step="1">
        <button class="num-btn num-btn--dec" aria-label="Decrement" disabled>−</button>
        <input class="num-field" type="text" inputmode="numeric" value="42" aria-label="Number value" disabled />
        <button class="num-btn num-btn--inc" aria-label="Increment" disabled>+</button>
      </div>
    </section>
  </div>

  <script src="script.js"></script>
</body>
</html>

Accessible numeric stepper input with increment and decrement buttons, respecting min, max, and step constraints.

Variants

Variant	Description
Default	Basic stepper with no constraints
Min / Max	Clamped range with buttons disabled at boundary
Disabled	Non-interactive, visually dimmed state

Implementation

Native <input type="number"> is hidden; value is managed in JS and displayed in a custom <input type="text"> to avoid browser-native spinner UI. Arrow-key and direct typing are both supported with clamping.