How to word wrap legend labels in d3.js?

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by darion , in category: Javascript , 15 days ago

How to word wrap legend labels in d3.js?

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1 answer

by ryan.murray , 14 days ago

@darion 

To word wrap legend labels in d3.js, you can adjust the text inside the legend by splitting it into multiple lines. Here's an example of how you can achieve this:

  1. Determine the maximum width for each line in the legend labels. You can use a fixed width or calculate it dynamically based on the available space.
  2. Split the legend labels into lines by inserting line breaks () at appropriate places.
  3. Update the HTML or SVG content of the legend labels using d3's .html() or .text() methods.


Here's a code snippet illustrating how to word wrap the labels of a simple legend using SVG and d3:

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// Example data for the legend
const legendData = ["Label 1", "Label 2", "Label 3 with a longer text"];

// SVG container for the legend
const svg = d3.select("svg");

// Width and height of the legend
const legendWidth = 200, legendHeight = 150;

// Add a group for the legend
const legend = svg.append("g")
  .attr("transform", "translate(10, 10)");

// Calculate the maximum width for each line
const maxLineWidth = Math.floor(legendWidth / 7); // Adjust the number to your needs

// Add legend labels
const labels = legend.selectAll("text")
  .data(legendData)
  .enter().append("text")
  .attr("x", 10)
  .attr("y", (_, i) => i * 20)
  .text(d => d)
  .each(function(d) {
    const words = d.split(" ");
    let line = "";
    const lineNumber = this.__data__.length > maxLineWidth ? 2 : 1; // Line number based on the maximum width of the label
    const lineHeight = 1.1; // Adjust the line height if needed
    const tspan = d3.select(this);
    tspan.text("");

    for (let i = 0; i < words.length; i++) {
      const tspanLine = tspan.append("tspan")
        .attr("x", 10)
        .attr("dy", i === 0 ? 0 : lineHeight + "em")
        .text(line + words[i]);
      
      // If the current line exceeds the maximum width, move the remaining words to the next line
      if (tspanLine.node().getComputedTextLength() > maxLineWidth) {
        line += words[i] + " ";
        tspanLine.text(line.trim());
        line = "";
        i--;
      } else {
        line += words[i] + " ";
      }
    }
  });


This code will split the legend labels into multiple lines if they exceed the maximum width specified by maxLineWidth. Adjust the maxLineWidth value, the line height, and any other styling attributes to fit your specific needs.