Category: JavaScript Answers

Sometimes, we want to get height of the highest children element in JavaScript.

In this article, we’ll look at how to get height of the highest children element in JavaScript.

How to get height of the highest children element in JavaScript?

To get height of the highest children element in JavaScript, we can select all the elements with querySelectorAll.

Then we can use the clientHeight property to get the height of each element.

For instance, we write:

<div style='height: 200px'>
  foo
</div>
<div>
  bar
</div>
<div style='height: 300px'>
  ba
</div>

to add some divs.

Then we get the height of the tallest div with:

const [tallest] = [...document.querySelectorAll('div')]
.sort((a, b) => b.clientHeight - a.clientHeight)
console.log(tallest.clientHeight)

We select all the divs with querySelectorAll.

Then we spread them into an array.

Next, we call sort to sort the divs by their height in descending order.

We get the height with the clientHeight property.

Then we get the tallest div with destructuring.

Therefore, tallest.clientHeight is 300 pixels according to the log.

Conclusion

To get height of the highest children element in JavaScript, we can select all the elements with querySelectorAll.

Then we can use the clientHeight property to get the height of each element.

Sometimes, we want to trigger clicks automatically with jQuery.

In this article, we’ll look at how to trigger clicks automatically with jQuery.

How to trigger clicks automatically with jQuery?

To trigger clicks automatically with jQuery. we can call the click method.

For instance, we write:

<button>
  hello
</button>

to add a button.

Then we write:

const button = $('button')
button.on('click', () => console.log('clicked'))

$(document).ready(() => {
  $(button).click();
});

We select the button with $('button').

Then we call on with 'click' and a click event handler to add an event handler.

Then we call click on the button when the document is loaded.

Therefore, we see 'clicked' logged when the page loads.

Conclusion

To trigger clicks automatically with jQuery. we can call the click method.

Sometimes, we want to find the largest palindrome made from the product of two 3-digit numbers with JavaScript.

In this article, we’ll look at how to find the largest palindrome made from the product of two 3-digit numbers with JavaScript.

How to find the largest palindrome made from the product of two 3-digit numbers with JavaScript?

To find the largest palindrome made from the product of two 3-digit numbers with JavaScript, we can loop through from 999 to 100 to find the products that create palindromes with another 3 digit number.

For instance, we write:

const isPalin = (i) => {
  return i.toString() === i.toString().split("").reverse().join("");
}

const largestPalindrome = () => {
  const arr = [];
  for (let i = 999; i > 100; i--) {
    for (let j = 999; j > 100; j--) {
      const mul = j * i;
      if (isPalin(mul)) {
        arr.push(j * i);
      }
    }
  }
  return Math.max(...arr);
}

console.log(largestPalindrome());

We create the isPalin function to check if i converted to a string is the same originally as if it has been reversed with reverse.

Then we define the largestPalindrome function that has a nested loop to find the products between j and i.

And we call isPalin to check if the product is a palindrome.

And then we call Math.max with the entries of arr spread as arguments.

Therefore, we see 906609 logged.

Conclusion

To find the largest palindrome made from the product of two 3-digit numbers with JavaScript, we can loop through from 999 to 100 to find the products that create palindromes with another 3 digit number.

Sometimes, we want to check if a date is today with JavaScript.

In this article, we’ll look at how to check if a date is today with JavaScript.

How to check if a date is today with JavaScript?

To check if a date is today with JavaScript, we can convert both dates to date strings before doing the comparison.

For instance, we write:

const today = new Date()
const today2 = new Date(2022, 0, 20)
const isSame = today.toDateString() === today2.toDateString();
console.log(isSame)

We create 2 Date instances, today and today2.

Then we call toDateString on both of them to convert them to date strings.

Then we can use === to compare the date strings.

If today is January 20, 2022, then isSame would be true.

Conclusion

To check if a date is today with JavaScript, we can convert both dates to date strings before doing the comparison.

Sometimes, we want to get the first property of a JSON object with JavaScript.

In this article, we’ll look at how to get the first property of a JSON object with JavaScript.

How to get the first property of a JSON object with JavaScript?

To get the first property of a JSON object with JavaScript, we can use the Object.keys method.

For instance, we write:

const json = `{
  "category1": ["image/url/1.jpg", "image/url/2.jpg"],
  "category2": ["image/url/3.jpg", "image/url/4.jpg"]
}`
const obj = JSON.parse(json)
const [key] = Object.keys(obj)
console.log(key)

to define the json JSON string.

Then we parse it into an object with JSON.parse.

Then we call Object.keys with obj to return an array of the object keys.

And we get the first one with destructuring.

As a result, we see that key is 'category1'.

Conclusion

To get the first property of a JSON object with JavaScript, we can use the Object.keys method.