<script> var c = document.getElementById('myCanvas'); var cricle = c.getContext('2d'); cricle.beginPath(); cricle.arc(100, 100, 50, 0*Math.PI, 2*Math.PI); cricle.stroke(); // stroke fill都可以
c.addEventListener('click', function(e) { var x = e.pageX; var y = e.pageY; var calX = x-100; var calY = y-100; var move = Math.sqrt(calX*calX + calY*calY); if(move < 50) { console.log('圆内') } else { console.log('圆外') }