JavaScript d3 带纵轴和 json 数据的折线图

Question

I am new creating charts with d3 and Im trying to build a line chart with ordinal axis. I have managed to visualize the y axis and the x axis correctly, but I am not able to create the line.

I have this code:

    var margin = {top: 10, right: 30, bottom: 30, left: 60},
    width = 460 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

    var data = [{
        name: "cat",
        value: 10
    }, {
        name: "dog",
        value: 3
    }, {
        name: "pig",
        value: 7
    }, {
        name: "bird",
        value: 7
    }];


    //append the svg object to the body of the page
    var svg = d3.select("#div-svg"  ).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 + ")");

    //set scale
    var xScale = d3.scaleBand()
            .domain(d3.extent(data, function(d){return d["name"]}))
            .range([0, width]),
        yScale = d3.scaleLinear()
            .domain([min(this.value_array), max(this.value_array)])
            .range([height, 0]);
       
    //add Axis
    svg.append("g")
        .attr("transform", "translate(0," + height + ")")
        .call(d3.axisBottom(xScale));

    svg.append("g")
        .call(d3.axisLeft(yScale));

Up to here everything works fine. The next part is the onethat doesn't work.

   //line
    var line = d3.line()
        .x(function(d) { return xScale(d[0]); }) 
        .y(function(d) { return yScale(d.value); }) 

If I put d[0] I get the following error " type number is not assignable to parameter of tye string ". If I put d.name I get the following error " 'name' does not exist on type [number,number] ". I don't know how to proceed to display the chart. Do you have any solution?

Also I would like it to be an area chart not just a linechart, in case the procedure changes.

Answer 1

d3.extent is not what you want to use for the domain. You need an array with each of the bar names.

var xScale = d3.scaleBand()
            .domain(data.map(function(d){return d["name"]}))
            .range([0, width])