我想要做的是获得一个函数，当我将鼠标移动到使用d3.json文件绘制的Map（USA）时，这将显示存储在CSV文件中的数据。
我遇到的问题是我不知道如何实现鼠标悬停功能，因为我不知道应该在哪里引用。
这是我的代码。我不知道该怎么做。任何提示都会非常感激。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>D3: Applying a projection to SVG paths</title>
<script type="text/javascript" src="../d3/d3.v3.js"></script>
<style type="text/css">
/* No style rules here yet */
</style>
</head>
<body>
<script type="text/javascript">
//Width and height
var w = 500;
var h = 300;
//Define map projection
var projection = d3.geo.albersUsa()
.translate([w/2, h/2])
.scale([500]);
//Define path generator
var path = d3.geo.path()
.projection(projection);
//Define quantize scale to sort data values into buckets of color
var color = d3.scale.quantize()
.range(["rgb(237,248,233)","rgb(186,228,179)","rgb(116,196,118)","rgb(49,163,84)","rgb(0,109,44)"]);
//Colors taken from colorbrewer.js, included in the D3 download
//Create SVG element
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
//Load in agriculture data
d3.csv("us-ag-productivity-2004.csv", function(data) {
//Set input domain for color scale
color.domain([
d3.min(data, function(d) { return d.value; }),
d3.max(data, function(d) { return d.value; })
]);
//Load in GeoJSON data
d3.json("us-states.json", function(json) {
//Merge the ag. data and GeoJSON
//Loop through once for each ag. data value
for (var i = 0; i < data.length; i++) {
//Grab state name
var dataState = data[i].state;
//Grab data value, and convert from string to float
var dataValue = parseFloat(data[i].value);
//Find the corresponding state inside the GeoJSON
for (var j = 0; j < json.features.length; j++) {
var jsonState = json.features[j].properties.name;
if (dataState == jsonState) {
//Copy the data value into the JSON
json.features[j].properties.value = dataValue;
//Stop looking through the JSON
break;
}
}
}
//Bind data and create one path per GeoJSON feature
svg.selectAll("path")
.data(json.features)
.enter()
.append("path")
.attr("d", path)
.style("fill", function(d) {
//Get data value
var value = d.properties.value;
if (value <1.15) {
//If value exists…
return color(value);
} else if (value >1.15) {
return "red"; }
else {
//If value is undefined…
return "#ccc";
}
});
});
});
</script>
</body>
</html>
你必须添加mousedown，mousemove，mouseup 3个事件
const target = document.getElementsByTagName("SVG");
// or by id
const target = document.getElementsById("someid");
target.addEventListener('mousedown', () => {
console.log('mousedown');
});
target.addEventListener('mousemove', () => {
console.log('mousemove');
});
target.addEventListener('mouseup', () => {
console.log('mouseup');
});
但我的事情d3.js处理这一切，检查官方文档。