Letter Count Bar Chart (d3v4)

Letter Count Bar Chart

In this demo, we asynchronously load a text file, use JavaScript to count the number of times each letter appears in that file, and generate a bar chart showing the letter count in D3.js v4.

This is meant to be an introductory demo to expose students to HTML, CSS, JavaScript, D3.js, bl.ocks.org, and blockbuilder.org for the first time.

References

This is based off the following example:

</sjengle/e8c0d6abc0a8d52d4b11>

It has been updated for D3.js v4 based on the following updated bar chart example:

https://bl.ocks.org/mbostock/3885304

Please see the original examples for videos and additional references.

forked from sjengle's block: Letter Count Bar Chart (d3v4)

forked from anonymous's block: Letter Count Bar Chart (d3v4)

<!DOCTYPE html>

<title>Letter Count Bar Chart</title>

<link href="https://fonts.googleapis.com/css?family=Roboto:300,300italic" rel="stylesheet" type="text/css">

<link href="style.css" rel="stylesheet" type="text/css">
</head>

<textarea></textarea>

<script src="https://d3js.org/d3.v4.min.js"></script>

<script src="count.js"></script>
<script src="chart.js"></script>

<script type="text/javascript">
// inside the script tag, // and /* */ are comments
// outside the script tag,  are comments

// we need to load the text file into the textarea
// this will be done asynchronously!
// https://github.com/d3/d3-request/blob/master/README.md#text
d3.text("peter.txt", function(error, data) {
    // we are creating a function within a method call here

if (error) throw error;

// we will use the console and developer tools extensively
    console.log(data);

// now we select the textarea from the DOM and update
    // https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model
    // https://github.com/d3/d3-selection/blob/master/README.md#select
    d3.select("body").select("textarea").text(data);

// updateData();
    drawBarChart();
});

// this message will appear BEFORE the text is logged!
console.log("after d3.text() call");

// add an event listener to our text area and
// update our chart every time new data is entered
d3.select("body").select("textarea")
  .on("keyup", drawBarChart);
</script>

</body>

https://d3js.org/d3.v4.min.js