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console 命令行工具 X clear

                    
>
console
var nodes = d3.range(100).map(function(i) {
    return {
        index: i
    };
});
var links = d3.range(nodes.length - 1).map(function(i) {
    return {
        source: Math.floor(Math.sqrt(i)),
        target: i + 1
    };
});
var simulation = d3.forceSimulation(nodes)
.force("charge", d3.forceManyBody())
.force("link", d3.forceLink(links).distance(20).strength(1))
.force("x", d3.forceX())
.force("y", d3.forceY())
.on("tick", ticked);
var canvas = document.querySelector("canvas"),
    context = canvas.getContext("2d"),
    width = canvas.width,
    height = canvas.height;
d3.select(canvas)
    .call(d3.drag()
          .container(canvas)
          .subject(dragsubject)
          .on("start", dragstarted)
          .on("drag", dragged)
          .on("end", dragended));
function ticked() {
    context.clearRect(0, 0, width, height);
    context.save();
    context.translate(width / 2, height / 2);
    context.beginPath();
    links.forEach(drawLink);
    context.strokeStyle = "#aaa";
    context.stroke();
    context.beginPath();
    nodes.forEach(drawNode);
    context.fill();
    context.strokeStyle = "#fff";
    context.stroke();
    context.restore();
}
function dragsubject() {
    return simulation.find(d3.event.x - width / 2, d3.event.y - height / 2);
}
function dragstarted() {
    if (!d3.event.active) simulation.alphaTarget(0.3).restart();
    d3.event.subject.fx = d3.event.subject.x;
    d3.event.subject.fy = d3.event.subject.y;
}
function dragged() {
    d3.event.subject.fx = d3.event.x;
    d3.event.subject.fy = d3.event.y;
}
function dragended() {
    if (!d3.event.active) simulation.alphaTarget(0);
    d3.event.subject.fx = null;
    d3.event.subject.fy = null;
}
function drawLink(d) {
    context.moveTo(d.source.x, d.source.y);
    context.lineTo(d.target.x, d.target.y);
}
function drawNode(d) {
    context.moveTo(d.x + 3, d.y);
    context.arc(d.x, d.y, 3, 0, 2 * Math.PI);
}
<canvas height="500" width="800"></canvas>
<svg class="chart"></svg>

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