D3.js，需要在d3.js中点击事件

Question

I am trying to make a bubble chart, in that if i click on a bubble, the title of the bubble should appear in the console. I tried some ways, but was not successful.

d3.json("deaths.json",
function (jsondata) {

    var deaths = jsondata.map(function(d) { return d.deaths; });
var infections = jsondata.map(function(d) { return d.infections; });
var country = jsondata.map(function(d) { return d.country; });
var death_rate = jsondata.map(function(d) { return d.death_rate; });

    console.log(deaths);
console.log(death_rate);
console.log(infections);
console.log(country);
console.log(date);

//Making chart

for (var i=0;i<11;i++)
{
var f;
var countryname=new Array();
var dot = new Array();
dot = svg.append("g").append("circle").attr("class", "dot").attr("id",i)
.style("fill", function(d) { return colorScale(death_rate[i]); }).call(position);       

//adding mouse listeners....

dot.on("click", click());
function click() 
{
     /***********************/
 console.log(country); //i need the title of the circle to be printed
     /*******************/
    }

function position(dot) 
{
dot .attr("cx", function(d) { return xScale(deaths[i]); })
    .attr("cy", function(d) { return yScale(death_rate[i]); })  
    .attr("r", function(d) { return radiusScale(infections[i]); });
dot.append("title").text(country[i]);
}
}
});

I need the title of circle to be printed Please help!!!

Answer 1

You had the good idea by using the on("click", ...) function. However I see two things:

• The first problem is that you don't call the function on the click event but its value. So, you write dot.on("click", click()); instead of dot.on("click", click); . To understand the difference, let's imagine that the function click needs one argument, which would for example represent the interesting dot, what would it be? Well, you would write the following:

   dot.on("click", function(d){click(d)}) 

  Which is equivalent (and less prone to errors) to writing:

   dot.on("click", click) 

• Now, the second point is that, indeed you want to pass the node as an argument of the function click . Fortunately, with the on event, as I used in my example, the function click is called with the argument d which represents the data of dot . Thus you can now write:

   dot.on("click", click); function click(d) { console.log(d.title); //considering dot has a title attribute } 

  Note: you can also use another argument by writing function click(d,i) with i representing the index in the array, see the documentation for more details.

Answer 2

如果您的数据有标题，

    dot.on('click' , function(d){ console.log(d.title); });