Category: JavaScript Answers

Sometimes, we want to clear an HTML file upload field via JavaScript.

In this article, we’ll look at how to clear an HTML file upload field via JavaScript.

How to clear an HTML file upload field via JavaScript?

To clear an HTML file upload field via JavaScript, we set the file input’s value property to an empty string.

For instance, we write

<form>
  <input id="fileInput" name="fileInput" type="file" />
</form>

to add a form with a file input.

Then we write

document.getElementById("fileInput").value = "";

to select the file input with getElementById.

And we set its value property to an empty string.

Conclusion

To clear an HTML file upload field via JavaScript, we set the file input’s value property to an empty string.

Sometimes, we want to add space between numbers with JavaScript.

In this article, we’ll look at how to add space between numbers with JavaScript.

How to add space between numbers with JavaScript?

To add space between numbers with JavaScript, we use the number toLocaleString method.

For instance, we write

const num = 1234567890;
const result = num.toLocaleString("fr");

to call num.toLocaleString with "fr" to return a number in the Frenchlocale.

This will return '1 234 567 890'.

Conclusion

To add space between numbers with JavaScript, we use the number toLocaleString method.

Sometimes, we want to use string replace with regex to strip off illegal characters with JavaScript.

In this article, we’ll look at how to use string replace with regex to strip off illegal characters with JavaScript.

How to use string replace with regex to strip off illegal characters with JavaScript?

To use string replace with regex to strip off illegal characters with JavaScript, we define a regex that match all the characters we want to remove.

For instance, we write

const cleanString = dirtyString.replace(/[|&;$%@"<>()+,]/g, "");

to call dirtyString.replace with a regex that matches anything in the square brackets.

The g flag makes replace replace all matches.

We replace each match with an empty string.

Conclusion

To use string replace with regex to strip off illegal characters with JavaScript, we define a regex that match all the characters we want to remove.

Sometimes, we want to replace all "%20" with a space with JavaScript.

In this article, we’ll look at how to replace all "%20" with a space with JavaScript.

How to replace all "%20" with a space with JavaScript?

To replace all "%20" with a space with JavaScript, we call the decodeURI function.

For instance, we write

const s = decodeURI(str);

to call decodeURI with str to return a string with all '%20' substrings removed from it.

Conclusion

To replace all "%20" with a space with JavaScript, we call the decodeURI function.

Sometimes, we want to generate a random number that is 9 digits in length with JavaScript.

In this article, we’ll look at how to generate a random number that is 9 digits in length with JavaScript.

How to generate a random number that is 9 digits in length with JavaScript?

To generate a random number that is 9 digits in length with JavaScript, we use the Math.random method.

For instance, we write

const n = Math.floor(100000000 + Math.random() * 900000000);

to use 100000000 + Math.random() * 900000000 to generate a number that’s 9 digits with decimal places.

Then we call Math.floor to round it down to between 100000000 and 999999999.

Conclusion

To generate a random number that is 9 digits in length with JavaScript, we use the Math.random method.