javascript - d3 无法读取未定义的属性 'classed'

Question

尝试通过获取当前路径的 pathID 并为其分配一个 class .highlight 来突出显示当前路径线，使 stroke-width: 2px。

console.log 显示current pathID 但它不想分配一个类。请帮忙。我在这里做错了什么？

Codepen

//Generate group (main)
    let groups = svg.selectAll("g")
        .data(dataset)
        .enter()
        .append("g")
        .on("mouseover", function(d) {
            d3.select(this)
                .call(revealCityName)
        })
        .on("mouseout", hideCityName)

//Path (path #, path line)
groups
    .append("path").classed("line", true)
    .attr("id", function(d) {
        console.log(d.country)
        if (d && d.length != 0) {
            return d.country.replace(/ |,|\./g, '_');
        }
    })
    .attr("d", d => line(d.emissions))
    .classed("unfocused", true)
    .style("stroke-width", d =>
        d.country === "China" ? 1 : 0.2
    )
    .on("mouseover", highlightPath);

//Text (contries on the left y axis)
groups
    .append("text")
    .datum(function(d) {
        return { country: d.country, value: d.emissions[d.emissions.length - 1]};
    })
    .attr("transform", function(d) {
        if (d.value) {
            return "translate(" + xScale(d.value.year) + "," + yScale(d.value.amount) + ")";
        } else {
            return null;
        }
    })
    .attr("x", 3)
    .attr("dy", 4)
    .style("font-size", 10)
    .style("font-family", "Abril Fatface")
    .text(d => d.country)
    .classed("hidden", function(d) {
        if (d.value && d.value.amount > 700000) {
            return false
        } else {
            return true;
        }
    })

还有一个我正在尝试分配类的函数:

    function highlightPath(d) {

    let pathID = d3.select(this).attr("id");

    console.log(pathID);

    let currentId = d3.select(this).select("path#" + pathID)
    console.log("Current ID: ",currentId)
    .classed("highlight", true);
}

Answer 1

console.log 正在拆分代码。这是错误:

function highlightPath(d) {

    let pathID = d3.select(this).attr("id");

    console.log(pathID);

    let currentId = d3.select(this).select("path#" + pathID)
    console.log("Current ID: ",currentId) /* <<<<<<<<< HERE (line 218 in your codepen) */ 
    .classed("highlight", true);
}

应该是:

function highlightPath(d) {

    let pathID = d3.select(this).attr("id");

    console.log(pathID);

    let currentId = d3.select(this).classed('highlight', true) // thanks to @shashank

    console.log("Current ID: ", currentId)
}

更新演示:https://codepen.io/anon/pen/qQRJXp

@Shashank 评论后更新

highlightPath is a mouseover event bound to the path which results in d3.select(this) to be the path itself and so you won't need any .select(path#pathID) in this case but just d3.select(this).classed('highlighted', true)