Author: John Au-Yeung

Sometimes, we want to call a JavaScript function at a specific time of day.

In this article, we’ll look at how to call a JavaScript function at a specific time of day.

How to call a JavaScript function at a specific time of day?

To call a JavaScript function at a specific time of day, we call setTimeout with the number of milliseconds between now and the date and time we want to call the function.

For instance, we write

const etaMs = new Date(2023, 0, 21, 17, 0).getTime() - Date.now();
const timeout = setTimeout(() => {}, etaMs);

to call setTimeout with the function we want to run after etaMs milliseconds has elapsed.

We subtract the timestamp of the future date time by the timestamp of the current timestamp to get the number of milliseconds to wait before we call the setTimeout callback.

Conclusion

To call a JavaScript function at a specific time of day, we call setTimeout with the number of milliseconds between now and the date and time we want to call the function.

Sometimes, we want to parse ISO 8601 date in JavaScript.

In this article, we’ll look at how to parse ISO 8601 date in JavaScript.

How to parse ISO 8601 date in JavaScript?

To parse ISO 8601 date in JavaScript, we can use the Date constructor.

For instance, we write

const d = new Date("2022-04-07T13:58:10.104Z");
console.log(d.toString());

to create a Date object with an ISO 8601 date time string.

Then we use toString to return the string version of the date.

Conclusion

To parse ISO 8601 date in JavaScript, we can use the Date constructor.

Sometimes, we want to change selected option by value in a HTML select element using JavaScript.

In this article, we’ll look at how to change selected option by value in a HTML select element using JavaScript.

How to change selected option by value in a HTML select element using JavaScript?

To change selected option by value in a HTML select element using JavaScript, we can set its value property.

For instance, we write

document.getElementById("sel").value = "bike";

to select the drop down with getElementById.

Then we set its value property to the value of the option element with the value we’re looking for.

Conclusion

To change selected option by value in a HTML select element using JavaScript, we can set its value property.

Sometimes, we want to remove color underneath lines from a Chart.js line charts with JavaScript.

In this article, we’ll look at how to remove color underneath lines from a Chart.js line charts with JavaScript.

How to remove color underneath lines from a Chart.js line charts with JavaScript?

To remove color underneath lines from a Chart.js line charts with JavaScript, we set the fill option to false.

For instance, we write

const data = {
  labels: ["January", "February", "March", "April", "May", "June", "July"],
  datasets: [
    {
      label: "Dataset",
      fill: false,
      data: [1, 2, 3],
    },
  ],
};

to set fill to false to remove the color underneath the lines in the line chart.

Conclusion

To remove color underneath lines from a Chart.js line charts with JavaScript, we set the fill option to false.

Sometimes, we want to convert object containing objects into array of objects with JavaScript.

In this article, we’ll look at how to convert object containing objects into array of objects with JavaScript.

How to convert object containing objects into array of objects with JavaScript?

To convert object containing objects into array of objects with JavaScript, we can use the Object.values method.

For instance, we write

const data = {
  a: { 0: "1" },
  b: { 1: "2" },
  c: { 2: "3" },
  d: { 3: "4" },
};

const newArrayDataOfOjbect = Object.values(data);

to call Object.values with data to return an array of property values from the data object.

Conclusion

To convert object containing objects into array of objects with JavaScript, we can use the Object.values method.