javascript - 如何从按钮运行 <script>

Question

我是新的网页设计，我正在使用 javascript 库绘制一棵树。我的问题是它是在页面加载时自动绘制的。我想要一个按钮并单击这幅画，但我找不到如何操作。尝试将函数传递给 JavaScript 文件，但传递它时我不知道在 html 文件中如何调用它。

这是 fiddle https://jsfiddle.net/nse4w959/

<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
        var treeData = [
     {
        "name": "Top Level",
        "parent": "null",
        "children": [
          {
            "name": "Level 2: A",
            "parent": "Top Level",
            "children": [
              {
                "name": "Son of A",
                "parent": "Level 2: A"
              },
              {
                "name": "Daughter of A",
                "parent": "Level 2: A"
              }
            ]
          },
          {
            "name": "Level 2: B",
            "parent": "Top Level"
          }
    ]
    }
    ];
    // ************** Generate the tree diagram  *****************
    var margin = {top: 40, right: 120, bottom: 20, left: 120},
    width = 960 - margin.right - margin.left,
    height = 500 - margin.top - margin.bottom;
    var i = 0;
    var tree = d3.layout.tree().size([height, width]);
    var diagonal = d3.svg.diagonal().projection(function(d) { return [d.x, d.y]; });
    var svg = d3.select("body").append("svg")
    .attr("width", width + margin.right + margin.left)
    .attr("height", height + margin.top + margin.bottom).append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
    root = treeData[0];
    update(root);
    function update(source) {
     // Compute the new tree layout.
    var nodes = tree.nodes(root).reverse(),
    links = tree.links(nodes);
    // Normalize for fixed-depth.nodes.forEach(function(d) { d.y = d.depth * 100; });
    // Declare the nodes…
    var node = svg.selectAll("g.node").data(nodes, function(d) { return d.id || (d.id = ++i); });
    // Enter the nodes.
    var nodeEnter = node.enter().append("g").attr("class", "node")
    .attr("transform", function(d) {
     return "translate(" + d.x + "," + d.y + ")"; });
    nodeEnter.append("circle").attr("r", 10).style("fill", "#fff");
    nodeEnter.append("text").attr("y", function(d) {
          return d.children || d._children ? -18 : 18; })
      .attr("dy", ".35em")
      .attr("text-anchor", "middle")
      .text(function(d) { return d.name; })
      .style("fill-opacity", 1);
    // Declare the links…
    var link = svg.selectAll("path.link")
    .data(links, function(d) { return d.target.id; });
     // Enter the links.
     link.enter().insert("path", "g")
      .attr("class", "link")
      .attr("d", diagonal);
    }
</script>

Answer 1

调用按钮最简单的方法是

<button onclick="update()">Update</button>