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Add a Tooltip to a D3 Element

curriculum/challenges/english/blocks/data-visualization-with-d3/587d7faa367417b2b2512bd6.md

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--description--

A tooltip shows more information about an item on a page when the user hovers over that item. There are several ways to add a tooltip to a visualization. This challenge uses the SVG title element.

title pairs with the text() method to dynamically add data to the bars.

--instructions--

Append a title element under each rect node. Then call the text() method with a callback function so the text displays the data value.

--hints--

Your code should have 9 title elements.

js
assert.lengthOf(document.querySelectorAll('title'), 9);

The first title element should have tooltip text of 12.

js
assert.strictEqual(document.querySelectorAll('title')[0]?.textContent, '12');

The second title element should have tooltip text of 31.

js
assert.strictEqual(document.querySelectorAll('title')[1]?.textContent, '31');

The third title element should have tooltip text of 22.

js
assert.strictEqual(document.querySelectorAll('title')[2]?.textContent, '22');

The fourth title element should have tooltip text of 17.

js
assert.strictEqual(document.querySelectorAll('title')[3]?.textContent, '17');

The fifth title element should have tooltip text of 25.

js
assert.strictEqual(document.querySelectorAll('title')[4]?.textContent, '25');

The sixth title element should have tooltip text of 18.

js
assert.strictEqual(document.querySelectorAll('title')[5]?.textContent, '18');

The seventh title element should have tooltip text of 29.

js
assert.strictEqual(document.querySelectorAll('title')[6]?.textContent, '29');

The eighth title element should have tooltip text of 14.

js
assert.strictEqual(document.querySelectorAll('title')[7]?.textContent, '14');

The ninth title element should have tooltip text of 9.

js
assert.strictEqual(document.querySelectorAll('title')[8]?.textContent, '9');

--seed--

--seed-contents--

html
<style>
  .bar:hover {
    fill: brown;
  }
</style>
<body>
  <script>
    const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];

    const w = 500;
    const h = 100;

    const svg = d3
      .select('body')
      .append('svg')
      .attr('width', w)
      .attr('height', h);

    svg
      .selectAll('rect')
      .data(dataset)
      .enter()
      .append('rect')
      .attr('x', (d, i) => i * 30)
      .attr('y', (d, i) => h - 3 * d)
      .attr('width', 25)
      .attr('height', (d, i) => d * 3)
      .attr('fill', 'navy')
      .attr('class', 'bar');
    // Add your code below this line



    // Add your code above this line

    svg
      .selectAll('text')
      .data(dataset)
      .enter()
      .append('text')
      .text(d => d)
      .attr('x', (d, i) => i * 30)
      .attr('y', (d, i) => h - (d * 3 + 3));
  </script>
</body>

--solutions--

html
<style>
  .bar:hover {
    fill: brown;
  }
</style>
<body>
  <script>
    const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];

    const w = 500;
    const h = 100;

    const svg = d3
      .select('body')
      .append('svg')
      .attr('width', w)
      .attr('height', h);

    svg
      .selectAll('rect')
      .data(dataset)
      .enter()
      .append('rect')
      .attr('x', (d, i) => i * 30)
      .attr('y', (d, i) => h - 3 * d)
      .attr('width', 25)
      .attr('height', (d, i) => d * 3)
      .attr('fill', 'navy')
      .attr('class', 'bar')
      .append('title')
      .text(d => d);

    svg
      .selectAll('text')
      .data(dataset)
      .enter()
      .append('text')
      .text(d => d)
      .attr('x', (d, i) => i * 30)
      .attr('y', (d, i) => h - (d * 3 + 3));
  </script>
</body>