console 命令行工具 X clear

console

 var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-5, 5, 5, -3]});
 var A = board.create('point',[-4,-2]);
 var B = board.create('point',[0,-2]);
 var p = board.create('line',[A,B],{name: 'p',withLabel: true, color: 'green'});
 var C = board.create('glider', [4, 0, p]);
 //glider：滑块，可以在直线p上进行左右滑动。
 
 var E = board.create('point', [1,4], {name: 'E',size:2, color: 'blue'});
 var q = board.create('line',[A,E],{name: 'q',withLabel: true, color: 'green'});
 var r = board.create('line',[B,E],{name: 'r',withLabel: true, color: 'green'});
 var F = board.create('glider', [0,0,q], {name: 'F',size:2, color: 'blue'});
 var s = board.create('line',[C,F],{name: 's',withLabel: true, color: 'green'});
 var G = board.create('intersection', [s, r,0], {name: 'G',size:2, color: 'blue'});
 var t = board.create('line',[A,G],{color: 'grey', dash:"2"});
 var u = board.create('line',[B,F],{color: 'grey', dash:"2"});
 var H = board.create('intersection', [t, u], {name: 'H',size:2, color: 'blue'});
 var v = board.create('line', [E,H],{color: 'grey', dash:"2"});
 var D = board.create('intersection', [p, v, 0]);

<!DOCTYPE HTML>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<title>JSXGraph template</title>
	<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
	<link href="https://cdn.jsdelivr.net/npm/jsxgraph/distrib/jsxgraph.css" rel="stylesheet" type="text/css" />
	<script src="https://cdn.jsdelivr.net/npm/jsxgraph/distrib/jsxgraphcore.js" type="text/javascript" charset="UTF-8">

	</script>
	<!-- The next line is optional: MathJax -->
	<script src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js" id="MathJax-script" async>

	</script>
</head>

<body>
<div id="jxgbox" class="jxgbox" style="width:500px; height:400px;"></div>

</body>

</html>