abd abd - 18 days ago 5
Javascript Question

d3-tip doesn't work in a multiline chart

I am just learning how to use d3-tip in a multiline chart. I took this example for practising: http://bl.ocks.org/d3noob/d8be922a10cb0b148cd5
I've added d3-tip to the code but the tooltip doesn't appear. The chart is displayed correctly, but when I check the console: "Uncaught TypeError: Cannot read property 'value' of undefined" pointing to this code line:

.html(function(d) {
return "<b>" + d.value + "</b>";
})


Here I show you the script:

<script src="d3/d3.min.js" charset="utf-8"></script>
<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script>

// Set the dimensions of the canvas / graph
var margin = {top: 30, right: 20, bottom: 30, left: 50},
width = 600 - margin.left - margin.right,
height = 270 - margin.top - margin.bottom;

// Parse the date / time
var parseDate = d3.time.format("%b %Y").parse;

// Set the ranges
var x = d3.time.scale().range([0, width]);
var y = d3.scale.linear().range([height, 0]);

// Define the axes
var xAxis = d3.svg.axis().scale(x)
.orient("bottom").ticks(5);

var yAxis = d3.svg.axis().scale(y)
.orient("left").ticks(5);


var tip = d3.tip()
.attr('class', 'd3-tip')
.offset([0, 5])
.direction('n')
.html(function(d) {
return "<b>" + d.value + "</b>";
})

// Define the line
var priceline = d3.svg.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.value); });


// Adds the svg canvas
var svg = d3.select("body")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform",
"translate(" + margin.left + "," + margin.top + ")");

svg.call(tip);

// Get the data
d3.csv("stocks.csv", function(error, data) {
data.forEach(function(d) {
d.date = parseDate(d.date);
d.value = +d.value;
});

// Scale the range of the data
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.value; })]);

// Nest the entries by symbol
var dataNest = d3.nest()
.key(function(d) {return d.name;})
.entries(data);

// Loop through each symbol / key
dataNest.forEach(function(d) {

svg.append("path")
.attr("class", "line")
.on('mouseover', tip.show)
.on('mouseout', tip.hide)
.attr("d", priceline(d.values))
});


// Add the X Axis
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);

// Add the Y Axis
svg.append("g")
.attr("class", "y axis")
.call(yAxis);

});

function type(d) {
d.value = +d.value;
return d;
}

</script>


I have changed many things, but I don't find the way. Any idea?
Thanks in advance.

Answer

You don't have any data bound to the elements you're calling the tooltip on. You don't need a loop, just use D3's data binding:

svg.selectAll("path")
    .data(dataNest)
    .enter()
    .append("path")
    .attr("class", "line")
    .on('mouseover', tip.show)
    .on('mouseout', tip.hide)
    .attr("d", function(d) { return priceline(d.values); });

You probably also want to redefine your tooltip function:

.html(function(d) {
  return "<b>" + d.key + "</b>";
});
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