Category: JavaScript Answers

Sometimes, we want to prevent "Invalid date" with Moment.js and JavaScript.

In this article, we’ll look at how to prevent "Invalid date" with Moment.js and JavaScript.

How to prevent "Invalid date" with Moment.js and JavaScript?

To prevent "Invalid date" with Moment.js and JavaScript, we can check if a date is valid with the isValid method.

For instance, we write:

console.log(moment('2022-01-01').isValid())
console.log(moment('abc').isValid())

to create moment objects with a valid and invalid date string.

Then we can call inValid on each to check if they’re valid dates.

Therefore, the first log should log true since it’s a valid and the 2nd one should log false since it’s not.

Conclusion

To prevent "Invalid date" with Moment.js and JavaScript, we can check if a date is valid with the isValid method.

Sometimes, we want to pass text input to a click handler with JavaScript.

In this article, we’ll look at how to pass text input to a click handler with JavaScript.

How to pass text input to a click handler with JavaScript?

To pass text input to a click handler with JavaScript, we can select it and reference it in the click handler.

For instance, we write:

<form>
  <input type="text" name="name" />
  <input type="button" value='submit' />
</form>

to add a form with a text and button input.

Then we write:

const button = document.querySelector('input[type="button"]')
const input = document.querySelector('input[type="text"]')

button.onclick = () => {
  console.log(input.value)
}

to select the button and the text input with querySelector.

Then we set button.onclick to a function that logs the input.value property which has the text input’s value.

Conclusion

To pass text input to a click handler with JavaScript, we can select it and reference it in the click handler.

Sometimes, we want to replace all the dots in a number with JavaScript.

In this article, we’ll look at how to replace all the dots in a number with JavaScript.

How to replace all the dots in a number with JavaScript?

To replace all the dots in a number with JavaScript, we can use the string replace method.

For instance, we write:

const value = '8.30'
const newValue = value.replace(/\./g, 'x');
console.log(newValue)

to call replace with a regex that matches all dots in the value string.

And we replace them all with 'x'.

Therefore, newValue is '8x30'.

Conclusion

To replace all the dots in a number with JavaScript, we can use the string replace method.

Sometimes, we want to copy some properties from an object in JavaScript.

In this article, we’ll look at how to copy some properties from an object in JavaScript.

How to copy some properties from an object in JavaScript?

To copy some properties from an object in JavaScript, we can use the destructuring syntax.

For instance, we write:

const user = {
  id: 123,
  firstName: 'John',
  lastName: 'Smith'
};
const {
  id,
  ...newUser
} = user;
console.log(newUser);

to get all properties from user except id and assign that to newUser with the destructuring syntax.

The ... operator returns an object with all the properties except for the ones that has already been destructured.

Therefore, newUser is {firstName: 'John', lastName: 'Smith'}.

Conclusion

To copy some properties from an object in JavaScript, we can use the destructuring syntax.