Category: JavaScript Answers

Sometimes, we want to clone a file input element in JavaScript.

In this article, we’ll look at how to clone a file input element in JavaScript.

How to clone a file input element in JavaScript?

To clone a file input element in JavaScript, we can use the cloneNode method.

For instance, we write:

<input type='file'>

to add a file input.

Then we write:

const input = document.querySelector('input')
const inputClone = input.cloneNode(true)
document.body.appendChild(inputClone)

to select the file input with querySelector.

Then we call input.cloneNode with true to do a deep clone of the input and return it.

Finally, we call document.body.appendChild with inputClone to append it as a child of the body element.

Conclusion

To clone a file input element in JavaScript, we can use the cloneNode method.

Sometimes, we want to check for the subtract key press with JavaScript.

In this article, we’ll look at how to check for the subtract key press with JavaScript.

How to check for the subtract key press with JavaScript?

To check for the subtract key press with JavaScript, we can listen to the keypress event and use the event key property to check which key is pressed.

For instance, we write:

window.onkeypress = (e) => {
  if (e.key === '-') {
    console.log('subtract pressed')
  }
}

to check if the subtract key is pressed with e.key === '-' in the window.

If it’s pressed, then we log 'subtract pressed'.

Conclusion

To check for the subtract key press with JavaScript, we can listen to the keypress event and use the event key property to check which key is pressed.

Sometimes, we want to cast a string to an array with JavaScript.

In this article, we’ll look at how to cast a string to an array with JavaScript.

How to cast a string to an array with JavaScript?

To cast a string to an array with JavaScript, we can use the spread operator.

For instance, we write:

const s = 'foo'
const arr = [...s]
console.log(arr)

to spread the characters of s into an array with the spread operator and assign the array to arr.

Therefore, arr is ['f', 'o', 'o'].

Conclusion

To cast a string to an array with JavaScript, we can use the spread operator.

Sometimes, we want to use a regex to get first word after slash in URL with JavaScript.

In this article, we’ll look at how to use a regex to get first word after slash in URL with JavaScript.

How to use a regex to get first word after slash in URL with JavaScript?

To use a regex to get first word after slash in URL with JavaScript, we can call the string’s replace method.

For instance, we write:

const s = window.location.pathname.replace(/^\/([^\/]*).*$/, '$1');
console.log(s)

to call replace on the current URL with a regex that gets the first word after the slash and returns it.

Conclusion

To use a regex to get first word after slash in URL with JavaScript, we can call the string’s replace method.

Sometimes, we want to check the format of date with moment.js and JavaScript.

In this article, we’ll look at how to check the format of date with moment.js and JavaScript.

How to check the format of date with moment.js and JavaScript?

To check the format of date with moment.js and JavaScript, we can use the moment.js’ isValid method.

For instance, we write:

const isValid = (d) => moment(d, 'DD-MMM-YYYY HH:mm a', true).isValid()

console.log(isValid('02-Mar-2022 01:01 AM'))
console.log(isValid('2022-02-03 01:01 AM'))

We define the isValid function that calls moment to try to parse the datetime string in 'DD-MMM-YYYY HH:mm a' format.

Then we call isValid to check if the datetime string is valid in the given format.

Therefore, datetimes that starts with a date, month and year separated by dashes and hours, minutes and AM or PM are valid.

As a result, the first console log is true and the 2nd one is false.

Conclusion

To check the format of date with moment.js and JavaScript, we can use the moment.js’ isValid method.