Author: John Au-Yeung

Sometimes, we want to listen for click events on pie charts in Chart.js with JavaScript.

In this article, we’ll look at how to listen for click events on pie charts in Chart.js with JavaScript.

How to listen for click events on pie charts in Chart.js with JavaScript?

To listen for click events on pie charts in Chart.js with JavaScript, we can add a onClick method into the chart object.

For instance, we write

<canvas id="myChart" width="200" height="200"></canvas>

to add a canvas.

Then we write

const ctx = document.getElementById("myChart").getContext("2d");
const myChart = new Chart(ctx, {
  type: "bar",
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [
      {
        label: "# of Votes",
        data: [12, 19, 3, 5, 2, 3],
        backgroundColor: [
          "rgba(255, 99, 132, 0.2)",
          "rgba(54, 162, 235, 0.2)",
          "rgba(255, 206, 86, 0.2)",
          "rgba(75, 192, 192, 0.2)",
          "rgba(153, 102, 255, 0.2)",
          "rgba(255, 159, 64, 0.2)",
        ],
        borderColor: [
          "rgba(255,99,132,1)",
          "rgba(54, 162, 235, 1)",
          "rgba(255, 206, 86, 1)",
          "rgba(75, 192, 192, 1)",
          "rgba(153, 102, 255, 1)",
          "rgba(255, 159, 64, 1)",
        ],
        borderWidth: 1,
      },
    ],
  },
  options: {
    scales: {
      yAxes: [
        {
          ticks: {
            beginAtZero: true,
          },
        },
      ],
    },
    onClick(e) {
      const activePoints = myChart.getElementsAtEvent(e);
      const selectedIndex = activePoints[0]._index;
      console.log(this.data.datasets[0].data[selectedIndex]);
    },
  },
});

to create a chart with the Chart constructor.

We call it with the ctx canvas context and the an object with the onClick method.

In it, we get the points with myChart.getElementsAtEvent.

Then we get the index of the clicked point with activePoints[0]._index.

Then we use this.data.datasets[0].data[selectedIndex]) to get the data for the point.

Conclusion

To listen for click events on pie charts in Chart.js with JavaScript, we can add a onClick method into the chart object.

Sometimes, we want to create a JavaScript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase.

In this article, we’ll look at how to create a JavaScript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase.

How to create a JavaScript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase?

To create a JavaScript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase, we can create a regex with all the patterns in it.

For instance, we write

const regex = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])[0-9a-zA-Z]{8,}$/;

to define the regex that matches all the patterns.

(?=.*\d) matches at least one digit.

(?=.*[a-z]) matches at least one lower case.

(?=.*[A-Z]) matches at least one upper case.

[a-zA-Z0-9]{8,} matches at least 8 from the mentioned characters.

Conclusion

To create a JavaScript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase, we can create a regex with all the patterns in it.

Sometimes, we want to convert time interval given in seconds into more human readable form with JavaScript.

In this article, we’ll look at how to convert time interval given in seconds into more human readable form with JavaScript.

How to convert time interval given in seconds into more human readable form with JavaScript?

To convert time interval given in seconds into more human readable form with JavaScript, we can use the moment duration humanize method.

For instance, we write

const duration = moment.duration(31536000);
console.log(duration.humanize());

to create a duration object by calling moment.duration with a timestamp in milliseconds.

Then we call duration.humanize to return a human readable string with the duration.

Conclusion

To convert time interval given in seconds into more human readable form with JavaScript, we can use the moment duration humanize method.