I am trying to construct a legend based on size using Carto VL, and am struggling to implement the solution posed in this Github thread.


I built a box to house the legend earlier in the code, here is the code I have so far that constructs the legend itself. What is this code missing?

const Legend = piceaLayer.viz.width.getLegendData(
                  width : ramp(($picea), [1, 2, 3]);
                 [{key: '10%', value: 10,
                   key: '50%', value: 50,
                   key: '100%', value: 100}]

               document.getElementById('legend').innerHTML = LegendList;

1 Answer 1


You are mixing the viz declaration with the getLegendData method to retrieve the metadata of your visualization.

So first declare your width property:

const viz = new carto.Viz(`
        width: ramp($total_damage, [5, 25, 50])
        color: opacity(white, 0.5)
        strokeWidth: 0

And then retrieve your legend data elsewhere:

layer.on('loaded', () => {

            // Request data for legend from the layer viz
            const widthLegend = layer.viz.width.getLegendData({

            let widthLegendList = '';

            // Create list elements for legend
            widthLegend.data.forEach((legend, index) => {

                widthLegendList +=
                    `<li><div class="circle" style="background: #DCDCDC; width:${legend.value}px; height:${legend.value}px;"></div> ${legend.key.toFixed(0)}</li>`;

            // Place list items in the content section of the title/legend box
            document.getElementById('content').innerHTML = widthLegendList;


The result is not very elegant but it works. You can see the full code here.

enter image description here

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