Category: JavaScript Answers

Sometimes, we want to auto start print HTML page using JavaScript.

In this article, we’ll look at how to auto start print HTML page using JavaScript.

How to auto start print HTML page using JavaScript?

To auto start print HTML page using JavaScript, we call print when the page is loaded.

For instance, we write

window.onload = () => {
  window.print();
};

to set window.onload to a function that’s called when the page finishes loading.

In it, we call window.print to open the print dialog.

Conclusion

To auto start print HTML page using JavaScript, we call print when the page is loaded.

Sometimes, we want to block users from closing a window in JavaScript.

In this article, we’ll look at how to block users from closing a window in JavaScript.

How to block users from closing a window in JavaScript?

To block users from closing a window in JavaScript, we can watch the beforeunload event.

For instance, we write

window.onbeforeunload = () => {
  return "";
};

to set window.onbeforeunload to a function that’s called when the beforeunload event.

The beforeunload event is triggered when we close the window.

An alert box will show when we close the tab if we have an event listener for the beforeunload event.

Conclusion

To block users from closing a window in JavaScript, we can watch the beforeunload event.

Sometimes, we want to convert Firebase timestamp to date and time with JavaScript.

In this article, we’ll look at how to convert Firebase timestamp to date and time with JavaScript.

How to convert Firebase timestamp to date and time with JavaScript?

To convert Firebase timestamp to date and time with JavaScript, we use the Date constructor.

For instance, we write

const timestamp = { nanoseconds: 0, seconds: 1562524200 };

console.log(new Date(timestamp.seconds * 1000));

We convert seconds to milliseconds by multiplying it by 1000.

Then we pass it into the Date constructor to convert it into a Date object.

Conclusion

To convert Firebase timestamp to date and time with JavaScript, we use the Date constructor.

Sometimes, we want to wait until all JavaScript files are loaded before executing JavaScript code.

In this article, we’ll look at how to wait until all JavaScript files are loaded before executing JavaScript code.

How to wait until all JavaScript files are loaded before executing JavaScript code?

To wait until all JavaScript files are loaded before executing JavaScript code, we can watch the load event.

For instance, we write

window.addEventListener("load", () => {
  // ...
});

to call addEventListener with 'load' and a function that’s called when all the JavaScript files are loaded.

We put the code that we want to run after all the JavaScript files are loaded in the callback.

Conclusion

To wait until all JavaScript files are loaded before executing JavaScript code, we can watch the load event.

Sometimes, we want to smooth scroll anchor links with JavaScript.

In this article, we’ll look at how to smooth scroll anchor links with JavaScript.

How to smooth scroll anchor links with JavaScript?

To smooth scroll anchor links with JavaScript, we call the window.scroll method.

For instance, we write

window.scroll({
  behavior: "smooth",
  left: 0,
  top: element.offsetTop,
});

to call scroll with an object that has the behavior property set to 'smooth' to do smooth scrolling.

And we set top to element.offsetTop to scroll to the top of the element.

Conclusion

To smooth scroll anchor links with JavaScript, we call the window.scroll method.