d3.js图表​​对象错误：“未捕获的SyntaxError：意外的标识符”； [英] d3.js chart object error: "Uncaught SyntaxError: Unexpected identifier"

问题描述

我正在用 D3.JS 制作力向图。示例代码摘自此处。在运行实时代码（此处）时，我可以解析我的个人 .JSON 文件，并能够制作图形。
脱机复制以下代码块后，在控制台上遇到错误，因为
未捕获的SyntaxError：意外的标识符在常量链接= data.links.map（d => Object.create（d））; 处，在以下代码中为第5行。我正在使用 Chrome

I am making a force-directed graph with D3.JS. The sample code is taken from here. While running the live code (here) I am able to parse my personal .JSON files and is able to make the graph. After I copied the following chunk of code offline, I encounter an error on the console as "Uncaught SyntaxError: Unexpected identifier" at const links = data.links.map(d => Object.create(d)); which is 5th line in the following code. I am using Chrome

data = FileAttachment("ppi.json").json()
height = 600
height = 600
chart = {
  const links = data.links.map(d => Object.create(d));
  const nodes = data.nodes.map(d => Object.create(d));

  const simulation = d3.forceSimulation(nodes)
      .force("link", d3.forceLink(links).id(d => d.id))
      .force("charge", d3.forceManyBody())
      .force("center", d3.forceCenter(width / 2, height / 2));

  const svg = d3.create("svg")
      .attr("viewBox", [0, 0, width, height]);

  const link = svg.append("g")
      .attr("stroke", "#999")
      .attr("stroke-opacity", 0.6)
    .selectAll("line")
    .data(links)
    .join("line")
      .attr("stroke-width", d => Math.sqrt(d.value));

  const node = svg.append("g")
      .attr("stroke", "#fff")
      .attr("stroke-width", 1.5)
    .selectAll("circle")
    .data(nodes)
    .join("circle")
      .attr("r", 5)
      .attr("fill", color)
      .call(drag(simulation));

  node.append("title")
      .text(d => d.id);

  simulation.on("tick", () => {
    link
        .attr("x1", d => d.source.x)
        .attr("y1", d => d.source.y)
        .attr("x2", d => d.target.x)
        .attr("y2", d => d.target.y);

    node
        .attr("cx", d => d.x)
        .attr("cy", d => d.y);
  });

  invalidation.then(() => simulation.stop());

  return svg.node();
}

// data = FileAttachment("ppi.json").json()
// height = 600
// height = 600
color = ƒ(d)

color = {
  const scale = d3.scaleOrdinal(d3.schemeCategory10);
  return d => scale(d.group);
}
drag = ƒ(simulation)

drag = simulation => {
  
  function dragstarted(d) {
    if (!d3.event.active) simulation.alphaTarget(0.3).restart();
    d.fx = d.x;
    d.fy = d.y;
  }
  
  function dragged(d) {
    d.fx = d3.event.x;
    d.fy = d3.event.y;
  }
  
  function dragended(d) {
    if (!d3.event.active) simulation.alphaTarget(0);
    d.fx = null;
    d.fy = null;
  }
  
  return d3.drag()
      .on("start", dragstarted)
      .on("drag", dragged)
      .on("end", dragended);
}
d3 = require("d3@5")

推荐答案

可观察笔记本使用的语言不是Java语言。 / a>。因此，使用Observable中的代码时需要小心。

The language used by the Observable notebooks is not Javascript.. As such, you need to be careful when using code from Observable.

尤其是：

• 请勿复制粘贴单元格的值，只粘贴它们的代码。

    color = ƒ(d) // don't copy this!
    
    // copy this
    color = {
      const scale = d3.scaleOrdinal(d3.schemeCategory10);
      return d => scale(d.group);
    }

• 带有花括号的声明仅存在于Observable中。您可以使用IIFE 或重构代码。


• 最后，要导入文件，请使用 d3.fetch 而不是仅可观察的 FileAttachment 。


• Declarations with curly braces only exist in Observable. You can either use IIFEs or refactor the code.
• Finally, to import files, use d3.fetch instead of the Observable-only FileAttachment.

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