D3.json: "Uncaught TypeError: Unable to read property" children "from undefined"

I am trying to use d3 as a tool for presenting biological data.

I am trying to open the following example in my Chrome browser so that I can understand how it works. Unfortunately, I get the following error message "Uncaught TypeError: Unable to read the properties of children from undefined."

http://bl.ocks.org/4063550

If you click the link, the source code for the .html and .json file will be displayed below the visualization results. Obviously, visualization works on the above page. I'm not sure what I can do wrong.

I copied the index.html file and the flare.json file to a directory on the web server. If I tried to download it from a local file, I got another error: XMLHttpRequest could not load the file: /// C: / Users / (..omitted ..) /flare.json. Cross-start requests are only supported for HTTP.

The flare.json file can indeed be downloaded from the web server (I can see its text content). It contains tree data that I am trying to execute.

Obviously, the flare.json file starts as follows:

{ "name": "flare", "children": [ ...

Unfortunately, d3.json has problems analyzing this information ...

If this helps, here is the .html file I'm trying to open in Chrome:

 <!DOCTYPE html> <html> <head> <title>heirarchical graph</title> <meta charset="utf-8"> <style> .node circle { fill: #fff; stroke: steelblue; stroke-width: 1.5px; } .node { font: 10px sans-serif; } .link { fill: none; stroke: #ccc; stroke-width: 1.5px; } </style> <script type="text/javascript" src="https://raw.github.com/mbostock/d3/master/d3.v2.min.js"> </script> </head> <body> <script> var diameter = 960; var tree = d3.layout.tree() .size([360, diameter / 2 - 120]) .separation(function(a, b) { return (a.parent == b.parent ? 1 : 2) / a.depth; }); var diagonal = d3.svg.diagonal.radial() .projection(function(d) { return [dy, dx / 180 * Math.PI]; }); var svg = d3.select("body").append("svg") .attr("width", diameter) .attr("height", diameter - 150) .append("g") .attr("transform", "translate(" + diameter / 2 + "," + diameter / 2 + ")"); d3.json("flare.json", function(error, root) { var nodes = tree.nodes(root), links = tree.links(nodes); var link = svg.selectAll(".link") .data(links) .enter().append("path") .attr("class", "link") .attr("d", diagonal); var node = svg.selectAll(".node") .data(nodes) .enter().append("g") .attr("class", "node") .attr("transform", function(d) { return "rotate(" + (dx - 90) + ")translate(" + dy + ")"; }) node.append("circle") .attr("r", 4.5); node.append("text") .attr("dy", ".31em") .attr("text-anchor", function(d) { return dx < 180 ? "start" : "end"; }) .attr("transform", function(d) { return dx < 180 ? "translate(8)" : "rotate(180)translate(-8)"; }) .text(function(d) { return d.name; }); }); d3.select(self.frameElement).style("height", diameter - 150 + "px"); </script> </body> </html> 

And here is the flare.json file:

 { "name": "flare", "children": [ { "name": "analytics", "children": [ { "name": "cluster", "children": [ {"name": "AgglomerativeCluster", "size": 3938}, {"name": "CommunityStructure", "size": 3812}, {"name": "HierarchicalCluster", "size": 6714}, {"name": "MergeEdge", "size": 743} ] }, { "name": "graph", "children": [ {"name": "BetweennessCentrality", "size": 3534}, {"name": "LinkDistance", "size": 5731}, {"name": "MaxFlowMinCut", "size": 7840}, {"name": "ShortestPaths", "size": 5914}, {"name": "SpanningTree", "size": 3416} ] }, { "name": "optimization", "children": [ {"name": "AspectRatioBanker", "size": 7074} ] } ] }, { "name": "animate", "children": [ {"name": "Easing", "size": 17010}, {"name": "FunctionSequence", "size": 5842}, { "name": "interpolate", "children": [ {"name": "ArrayInterpolator", "size": 1983}, {"name": "ColorInterpolator", "size": 2047}, {"name": "DateInterpolator", "size": 1375}, {"name": "Interpolator", "size": 8746}, {"name": "MatrixInterpolator", "size": 2202}, {"name": "NumberInterpolator", "size": 1382}, {"name": "ObjectInterpolator", "size": 1629}, {"name": "PointInterpolator", "size": 1675}, {"name": "RectangleInterpolator", "size": 2042} ] }, {"name": "ISchedulable", "size": 1041}, {"name": "Parallel", "size": 5176}, {"name": "Pause", "size": 449}, {"name": "Scheduler", "size": 5593}, {"name": "Sequence", "size": 5534}, {"name": "Transition", "size": 9201}, {"name": "Transitioner", "size": 19975}, {"name": "TransitionEvent", "size": 1116}, {"name": "Tween", "size": 6006} ] }, { "name": "data", "children": [ { "name": "converters", "children": [ {"name": "Converters", "size": 721}, {"name": "DelimitedTextConverter", "size": 4294}, {"name": "GraphMLConverter", "size": 9800}, {"name": "IDataConverter", "size": 1314}, {"name": "JSONConverter", "size": 2220} ] }, {"name": "DataField", "size": 1759}, {"name": "DataSchema", "size": 2165}, {"name": "DataSet", "size": 586}, {"name": "DataSource", "size": 3331}, {"name": "DataTable", "size": 772}, {"name": "DataUtil", "size": 3322} ] }, { "name": "display", "children": [ {"name": "DirtySprite", "size": 8833}, {"name": "LineSprite", "size": 1732}, {"name": "RectSprite", "size": 3623}, {"name": "TextSprite", "size": 10066} ] }, { "name": "flex", "children": [ {"name": "FlareVis", "size": 4116} ] }, { "name": "physics", "children": [ {"name": "DragForce", "size": 1082}, {"name": "GravityForce", "size": 1336}, {"name": "IForce", "size": 319}, {"name": "NBodyForce", "size": 10498}, {"name": "Particle", "size": 2822}, {"name": "Simulation", "size": 9983}, {"name": "Spring", "size": 2213}, {"name": "SpringForce", "size": 1681} ] }, { "name": "query", "children": [ {"name": "AggregateExpression", "size": 1616}, {"name": "And", "size": 1027}, {"name": "Arithmetic", "size": 3891}, {"name": "Average", "size": 891}, {"name": "BinaryExpression", "size": 2893}, {"name": "Comparison", "size": 5103}, {"name": "CompositeExpression", "size": 3677}, {"name": "Count", "size": 781}, {"name": "DateUtil", "size": 4141}, {"name": "Distinct", "size": 933}, {"name": "Expression", "size": 5130}, {"name": "ExpressionIterator", "size": 3617}, {"name": "Fn", "size": 3240}, {"name": "If", "size": 2732}, {"name": "IsA", "size": 2039}, {"name": "Literal", "size": 1214}, {"name": "Match", "size": 3748}, {"name": "Maximum", "size": 843}, { "name": "methods", "children": [ {"name": "add", "size": 593}, {"name": "and", "size": 330}, {"name": "average", "size": 287}, {"name": "count", "size": 277}, {"name": "distinct", "size": 292}, {"name": "div", "size": 595}, {"name": "eq", "size": 594}, {"name": "fn", "size": 460}, {"name": "gt", "size": 603}, {"name": "gte", "size": 625}, {"name": "iff", "size": 748}, {"name": "isa", "size": 461}, {"name": "lt", "size": 597}, {"name": "lte", "size": 619}, {"name": "max", "size": 283}, {"name": "min", "size": 283}, {"name": "mod", "size": 591}, {"name": "mul", "size": 603}, {"name": "neq", "size": 599}, {"name": "not", "size": 386}, {"name": "or", "size": 323}, {"name": "orderby", "size": 307}, {"name": "range", "size": 772}, {"name": "select", "size": 296}, {"name": "stddev", "size": 363}, {"name": "sub", "size": 600}, {"name": "sum", "size": 280}, {"name": "update", "size": 307}, {"name": "variance", "size": 335}, {"name": "where", "size": 299}, {"name": "xor", "size": 354}, {"name": "_", "size": 264} ] }, {"name": "Minimum", "size": 843}, {"name": "Not", "size": 1554}, {"name": "Or", "size": 970}, {"name": "Query", "size": 13896}, {"name": "Range", "size": 1594}, {"name": "StringUtil", "size": 4130}, {"name": "Sum", "size": 791}, {"name": "Variable", "size": 1124}, {"name": "Variance", "size": 1876}, {"name": "Xor", "size": 1101} ] }, { "name": "scale", "children": [ {"name": "IScaleMap", "size": 2105}, {"name": "LinearScale", "size": 1316}, {"name": "LogScale", "size": 3151}, {"name": "OrdinalScale", "size": 3770}, {"name": "QuantileScale", "size": 2435}, {"name": "QuantitativeScale", "size": 4839}, {"name": "RootScale", "size": 1756}, {"name": "Scale", "size": 4268}, {"name": "ScaleType", "size": 1821}, {"name": "TimeScale", "size": 5833} ] }, { "name": "util", "children": [ {"name": "Arrays", "size": 8258}, {"name": "Colors", "size": 10001}, {"name": "Dates", "size": 8217}, {"name": "Displays", "size": 12555}, {"name": "Filter", "size": 2324}, {"name": "Geometry", "size": 10993}, { "name": "heap", "children": [ {"name": "FibonacciHeap", "size": 9354}, {"name": "HeapNode", "size": 1233} ] }, {"name": "IEvaluable", "size": 335}, {"name": "IPredicate", "size": 383}, {"name": "IValueProxy", "size": 874}, { "name": "math", "children": [ {"name": "DenseMatrix", "size": 3165}, {"name": "IMatrix", "size": 2815}, {"name": "SparseMatrix", "size": 3366} ] }, {"name": "Maths", "size": 17705}, {"name": "Orientation", "size": 1486}, { "name": "palette", "children": [ {"name": "ColorPalette", "size": 6367}, {"name": "Palette", "size": 1229}, {"name": "ShapePalette", "size": 2059}, {"name": "SizePalette", "size": 2291} ] }, {"name": "Property", "size": 5559}, {"name": "Shapes", "size": 19118}, {"name": "Sort", "size": 6887}, {"name": "Stats", "size": 6557}, {"name": "Strings", "size": 22026} ] }, { "name": "vis", "children": [ { "name": "axis", "children": [ {"name": "Axes", "size": 1302}, {"name": "Axis", "size": 24593}, {"name": "AxisGridLine", "size": 652}, {"name": "AxisLabel", "size": 636}, {"name": "CartesianAxes", "size": 6703} ] }, { "name": "controls", "children": [ {"name": "AnchorControl", "size": 2138}, {"name": "ClickControl", "size": 3824}, {"name": "Control", "size": 1353}, {"name": "ControlList", "size": 4665}, {"name": "DragControl", "size": 2649}, {"name": "ExpandControl", "size": 2832}, {"name": "HoverControl", "size": 4896}, {"name": "IControl", "size": 763}, {"name": "PanZoomControl", "size": 5222}, {"name": "SelectionControl", "size": 7862}, {"name": "TooltipControl", "size": 8435} ] }, { "name": "data", "children": [ {"name": "Data", "size": 20544}, {"name": "DataList", "size": 19788}, {"name": "DataSprite", "size": 10349}, {"name": "EdgeSprite", "size": 3301}, {"name": "NodeSprite", "size": 19382}, { "name": "render", "children": [ {"name": "ArrowType", "size": 698}, {"name": "EdgeRenderer", "size": 5569}, {"name": "IRenderer", "size": 353}, {"name": "ShapeRenderer", "size": 2247} ] }, {"name": "ScaleBinding", "size": 11275}, {"name": "Tree", "size": 7147}, {"name": "TreeBuilder", "size": 9930} ] }, { "name": "events", "children": [ {"name": "DataEvent", "size": 2313}, {"name": "SelectionEvent", "size": 1880}, {"name": "TooltipEvent", "size": 1701}, {"name": "VisualizationEvent", "size": 1117} ] }, { "name": "legend", "children": [ {"name": "Legend", "size": 20859}, {"name": "LegendItem", "size": 4614}, {"name": "LegendRange", "size": 10530} ] }, { "name": "operator", "children": [ { "name": "distortion", "children": [ {"name": "BifocalDistortion", "size": 4461}, {"name": "Distortion", "size": 6314}, {"name": "FisheyeDistortion", "size": 3444} ] }, { "name": "encoder", "children": [ {"name": "ColorEncoder", "size": 3179}, {"name": "Encoder", "size": 4060}, {"name": "PropertyEncoder", "size": 4138}, {"name": "ShapeEncoder", "size": 1690}, {"name": "SizeEncoder", "size": 1830} ] }, { "name": "filter", "children": [ {"name": "FisheyeTreeFilter", "size": 5219}, {"name": "GraphDistanceFilter", "size": 3165}, {"name": "VisibilityFilter", "size": 3509} ] }, {"name": "IOperator", "size": 1286}, { "name": "label", "children": [ {"name": "Labeler", "size": 9956}, {"name": "RadialLabeler", "size": 3899}, {"name": "StackedAreaLabeler", "size": 3202} ] }, { "name": "layout", "children": [ {"name": "AxisLayout", "size": 6725}, {"name": "BundledEdgeRouter", "size": 3727}, {"name": "CircleLayout", "size": 9317}, {"name": "CirclePackingLayout", "size": 12003}, {"name": "DendrogramLayout", "size": 4853}, {"name": "ForceDirectedLayout", "size": 8411}, {"name": "IcicleTreeLayout", "size": 4864}, {"name": "IndentedTreeLayout", "size": 3174}, {"name": "Layout", "size": 7881}, {"name": "NodeLinkTreeLayout", "size": 12870}, {"name": "PieLayout", "size": 2728}, {"name": "RadialTreeLayout", "size": 12348}, {"name": "RandomLayout", "size": 870}, {"name": "StackedAreaLayout", "size": 9121}, {"name": "TreeMapLayout", "size": 9191} ] }, {"name": "Operator", "size": 2490}, {"name": "OperatorList", "size": 5248}, {"name": "OperatorSequence", "size": 4190}, {"name": "OperatorSwitch", "size": 2581}, {"name": "SortOperator", "size": 2023} ] }, {"name": "Visualization", "size": 16540} ] } ] } 
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5 answers

The code is from d3.v3, but it points to d3.v2, which does not use the error call in the d3.json function.

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To make it work, I had to replace the line

 d3.json("flare.json", function(error, root) { 

from

 d3.json("flare.json", function(root) { 

I used my intuition here, and I still do not understand how this works on the example of a website, not mine, or what the true meaning of my change in code is. If you know how to answer this in more detail, please do your part and I will accept your answer.

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This is because the returned json object is accepted by the first parameter of the function. This may be due to d3 versions.

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Had the exact same error. The solution is quite simple: you do not provide an array of JSON objects. You said your JSON started as follows:

{ "name": "flare", "children": [ ...

Please change so that the change starts as follows:

[{ "name": "flare", "children": [ ...}]

Thus, D3 will be able to find the "first child "

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 <script> function liveProject() { var a=200; this. x=600; this. y=300; this. z= function () { return this.x+this.y; } } var lp=new liveProject(); document.write(lp.z()); </script> 
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