Radar sweep

A radar scope whose sweep leaves a phosphor afterglow and picks up moving contacts, the pointer among them, with a ping on click.

element
radar
sweep
glow
pointer
canvas
since 0.2

Background Studio: tune it below, then copy the code

Your system asks for reduced motion: the demo shows its final state and nothing moves.

Live demo

Radar sweep example

Code

It follows the controls above: change an option and the code changes with it.

<script src="https://search.axi0.io/axi0/motion/motion.js" defer></script>

<axi0-radar-sweep cover></axi0-radar-sweep>

import { RadarSweep } from "./motion/react/RadarSweep";

<RadarSweep />

<script setup lang="ts">
import RadarSweep from "./motion/vue/RadarSweep.vue";
</script>

<template>
  <RadarSweep />
</template>

const fx = document.createElement("axi0-radar-sweep");
document.querySelector("#hero").append(fx);

The wrappers: RadarSweep.tsx (React, TypeScript) and RadarSweep.vue (Vue). Both render the same attributes as the HTML; the loader does the rest.

Options

Attribute	Default	What it does
`period`	`4`	Seconds for one turn of the sweep
`contacts`	`6`	Moving contacts on the scope
`rings`	`4`	Range rings
`colors`	auto	Colors, comma separated (empty: the palette for the page's theme)
`background`	auto	Background color (empty: the theme's)
`speed`	`1`	How fast it moves
`theme`	`auto`	Light or dark palette (auto: from the page behind it)
`cover`	`false`	Fill the nearest positioned parent, behind its content

Decorative: the canvas is aria-hidden and takes no focus; with cover it ignores the pointer, so the content above it stays clickable. The contacts move on their own, so keyboard and touch users see the same scope; a tap pings like a click. Drawn on a 2D canvas at device resolution (capped at 2); it starts when it comes within 300 px of the screen, the frame loop stops off screen and in hidden tabs, and reduced motion draws one still frame with no movement.

Size

radar-sweep.js is 1.5 KB gzip, with backgrounds-kit.js 3.4 KB it needs. A page loads the loader (2.9 KB) and core.js (1.4 KB) once, whatever it uses.