Category: JavaScript Answers

Sometimes, we want to force a page scroll position to the top at page refresh with JavaScript.

In this article, we’ll look at how to force a page scroll position to the top at page refresh with JavaScript.

Force a Page Scroll Position to the Top at Page Refresh with JavaScript

To force a page scroll position to the top at page refresh with JavaScript, we can use the window.scrollTo method to scroll the page to the position we want in the beforeunload event handler.

For instance, we can write:

window.onbeforeunload = () => {  
  window.scrollTo(0, 0);  
};

to a function that calls window.scrollTo method with the x and y coordinates of the page to scroll to as the page is being refreshed.

Conclusion

To force a page scroll position to the top at page refresh with JavaScript, we can use the window.scrollTo method to scroll the page to the position we want in the beforeunload event handler.

Sometimes, we want to convert a JavaScript string into an array of integers.

In this article, we’ll look at how to convert a JavaScript string into an array of integers.

Convert a JavaScript String into an Array of Integers

To convert a JavaScript string into an array of integers, we can use the JavaScript string’s split method with the array filter method to keep only the numbers.

Then we call map with Number to convert all the values into numbers.

For instance, we can write:

const str = "5 6 7 69 foo"
const intArray = str.split(" ").map(Number).filter(Boolean);
console.log(intArray)

We have the str string which we want to extract the numbers from and put them into the array.

To do that, we call split with a space string to split the string by its spaces and put the split strings into an array.

Then we call map with Number to convert all the values into numbers.

Then we call filter to filter the items that aren’t numbers.

NaN is falsy so any value that can’t be converted to numbers is filtered out.

Therefore, intArray is:

[5, 6, 7, 69]

Conclusion

To convert a JavaScript string into an array of integers, we can use the JavaScript string’s split method with the array filter method to keep only the numbers.

Then we call map with Number to convert all the values into numbers.

Sometimes, we want to use JavaScript speech synthesis with longer texts.

In this article, we’ll look at how to use JavaScript speech synthesis with longer texts.

Use JavaScript Speech Synthesis with Longer Texts

To use JavaScript speech synthesis with longer texts, we can create a function to resume the utterance of the text.

Then we can resume the utterance when the start event is emitted.

For instance, we can write:

const text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.'
const utterance = new SpeechSynthesisUtterance(text);
window.speechSynthesis.speak(utterance);

const resumeInfinity = () => {
  window.speechSynthesis.resume();
  timeoutResumeInfinity = setTimeout(resumeInfinity, 1000);
}

utterance.onstart = (event) => {
  resumeInfinity();
};

utterance.onend = (event) => {
  clearTimeout(timeoutResumeInfinity);
};

We speak the text with:

const text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.'
const utterance = new SpeechSynthesisUtterance(text);
window.speechSynthesis.speak(utterance);

Then we create the resumeInfinity function which calls window.speechSynthesis.resume to continue speaking the text.

Then we create the timeoutResumeInfinity timer to call resumeInfinity after 1 second.

We call resumeInfinity in the onstart method so that the text is spoken until it reaches the end.

And in the onend method, we call clearTimeout with timeoutResumeInfinity to clear the timer.

Conclusion

To use JavaScript speech synthesis with longer texts, we can create a function to resume the utterance of the text.

Then we can resume the utterance when the start event is emitted.

Sometimes, we want to create a form dynamically with JavaScript.

In this article, we’ll look at how to create a form dynamically with JavaScript.

Create a Form Dynamically with JavaScript

To create a form dynamically with JavaScript, we can use the document.createElement method to create the element.

Then we can use the setAttribute method to set the element attributes.

Then we can use the appendChild method to append the elements into the parent element.

For instance, we can write:

const f = document.createElement("form");
f.setAttribute('method', "post");
f.setAttribute('action', "submit.php");

const i = document.createElement("input");
i.setAttribute('type', "text");
i.setAttribute('name', "username");

const s = document.createElement("input");
s.setAttribute('type', "submit");
s.setAttribute('value', "Submit");

f.appendChild(i);
f.appendChild(s);

document.body.appendChild(f);

to create a form with an input and a submit button.

We write:

const f = document.createElement("form");
f.setAttribute('method', "post");
f.setAttribute('action', "submit.php");

to create a form element with the method and action attributes.

setAttribute takes the attribute name and value as arguments respectively.

Similar, we create the input by writing:

const i = document.createElement("input");
i.setAttribute('type', "text");
i.setAttribute('name', "username");

And the submit button we create by writing:

const s = document.createElement("input");
s.setAttribute('type', "submit");
s.setAttribute('value', "Submit");

Next, we call appendChild on f to append both input elements as children of the form element by writing:

f.appendChild(i);
f.appendChild(s);

And finally, we append the form element as a child of the body element by writing:

document.body.appendChild(f);

Now we should see a form displayed on the screen after running the code that generated from the form.

Conclusion

To create a form dynamically with JavaScript, we can use the document.createElement method to create the element.

Then we can use the setAttribute method to set the element attributes.

Then we can use the appendChild method to append the elements into the parent element.

Sometimes, we want to create an empty array of a given size with JavaScript.

In this article, we’ll look at how to create an empty array of a given size with JavaScript.

Create an Empty Array of a Given Size with JavaScript

To create an empty array of a given size with JavaScript, we can use the Array constructor.

For instance, we can write:

const arr = new Array(5);  
console.log(arr.length)

to create an empty array with length 5 by passing in the length as the argument for the Array constructor.

Therefore, arr.length is 5 according to the console log.

Conclusion

To create an empty array of a given size with JavaScript, we can use the Array constructor.