iOS Style Segmented Controls In JavaScript & CSS

Preview:

Description:

Just another Vanilla JavaScript & CSS solution that converts a group of radio buttons into iOS style segmented controls introduced in Human Interface Guidelines.

How to use it:

1. Create a group of radio buttons.

<div class="ios-segmented-control">
  <span class="selection"></span>
  <div class="option">
    <input type="radio" id="metro" name="sample" value="metro" checked>
    <label for="metro"><span>Metro</span></label>
  </div>
  <div class="option">
    <input type="radio" id="bus" name="sample" value="bus">
    <label for="bus"><span>Bus</span></label>
  </div>
  <div class="option">
    <input type="radio" id="train" name="sample" value="train">
    <label for="train"><span>Train</span></label>
  </div>
</div>

2. The necessary CSS styles for the segmented control.

.ios-segmented-control {
  --background: rgba(239,239,240,1);
  background: var(--background);
  border-radius: 9px;
  margin: 0;
  padding: 2px;
  border: none;
  outline: none;
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 1fr;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}
.ios-segmented-control .option {
  position: relative;
  cursor: pointer;
}
.ios-segmented-control .option:hover input:not(:checked) + label span, .ios-segmented-control .option:active input:not(:checked) + label span, .ios-segmented-control .option:focus input:not(:checked) + label span {
  opacity: .2;
}
.ios-segmented-control .option:active input:not(:checked) + label span {
  transform: scale(.95);
}
.ios-segmented-control .option label {
  position: relative;
  display: block;
  text-align: center;
  padding: 3px 6vmin;
  background: rgba(255,255,255,0);
  font-weight: 500;
  color: rgba(0,0,0,1);
  font-size: 14px;
}
.ios-segmented-control .option label::before, .ios-segmented-control .option label::after {
  content: '';
  width: 1px;
  background: rgba(142,142,147,.15);
  position: absolute;
  top: 14%;
  bottom: 14%;
  border-radius: 10px;
  will-change: background;
  -webkit-transition: background .2s ease;
  transition: background .2s ease;
}
.ios-segmented-control .option label::before {
  left: 0;
  transform: translateX(-.5px);
}
.ios-segmented-control .option label::after {
  right: 0;
  transform: translateX(.5px);
}
.ios-segmented-control .option:first-of-type {
  grid-column: 1;
  grid-row: 1;
  box-shadow: none;
}
.ios-segmented-control .option:first-of-type label::before {
  opacity: 0;
}
.ios-segmented-control .option:last-of-type label::after {
  opacity: 0;
}
.ios-segmented-control .option input {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  outline: none;
  border: none;
  opacity: 0;
}
.ios-segmented-control .selection {
  background: rgba(255,255,255,1);
  border: .5px solid rgba(0,0,0,0.04);
  box-shadow: 0 3px 8px 0 rgba(0,0,0,0.12), 0 3px 1px 0 rgba(0,0,0,0.04);
  border-radius: 7px;
  grid-column: 1;
  grid-row: 1;
  z-index: 2;
  will-change: transform;
  -webkit-transition: transform .2s ease;
  transition: transform .2s ease;
}
.ios-segmented-control .option label span {
  display: block;
  position: relative;
  z-index: 2;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  will-change: transform;
}
.ios-segmented-control .option input:checked+label::before, .ios-segmented-control .option input:checked+label::after {
  background: var(--background);
  z-index: 1;
}
.ios-segmented-control .option input:checked+label {
  cursor: default;
}

3. The core JavaScript to activate the Segmented Control.

// Constants
const SEGMENTED_CONTROL_BASE_SELECTOR = ".ios-segmented-control";
const SEGMENTED_CONTROL_INDIVIDUAL_SEGMENT_SELECTOR = ".ios-segmented-control .option input";
const SEGMENTED_CONTROL_BACKGROUND_PILL_SELECTOR = ".ios-segmented-control .selection";

// Main
document.addEventListener("DOMContentLoaded", setup);
// Body functions
function setup() {
  forEachElement(SEGMENTED_CONTROL_BASE_SELECTOR, elem => {
    elem.addEventListener("change", updatePillPosition);
  })
  window.addEventListener("resize", updatePillPosition); // Prevent pill from detaching from element when window resized. Becuase this is rare I haven't bothered with throttling the event
}
function updatePillPosition() {
  forEachElement(SEGMENTED_CONTROL_INDIVIDUAL_SEGMENT_SELECTOR, (elem, index) => {
    if (elem.checked) moveBackgroundPillToElement(elem, index);
  })
}
function moveBackgroundPillToElement(elem, index) {
  document.querySelector(SEGMENTED_CONTROL_BACKGROUND_PILL_SELECTOR).style.transform = "translateX(" + (elem.offsetWidth * index) + "px)";
}
// Helper functions
function forEachElement(className, fn) {
  Array.from(document.querySelectorAll(className)).forEach(fn);
}