Category: JavaScript

Sometimes, we want to remove values from select list based on condition with JavaScript.

In this article, we’ll look at how to remove values from select list based on condition with JavaScript.

How to remove values from select list based on condition with JavaScript?

To remove values from select list based on condition with JavaScript, we can watch the selected value of the drop down.

Then we can remove the values accordingly.

For instance, we write:

<select>
  <option value="A">Apple</option>
  <option value="C">Cars</option>
  <option value="H">Honda</option>
  <option value="F">Fiat</option>
  <option value="I">Indigo</option>
</select>

to add a select drop down.

Then we write:

const select = document.querySelector("select");

select.addEventListener('change', () => {
  if (select.value === 'F') {
    const aIndex = [...select.options].findIndex(o => o.value === 'A')
    select.options.remove(aIndex);
    const cIndex = [...select.options].findIndex(o => o.value === 'C')
    select.options.remove(cIndex);
  }
})

We get the select element with document.querySelector.

Then we add a change event listener with addEventListener.

In the event listener, we check if select.value if 'F'.

If it is, then we get the ones that we want to remove by spreading the options into an array.

Then we call findIndex with a function that checks the value of the option to look for the index of the ones we want to remove.

Then we call select.options.remove to remove them.

Now when we select Fiat, we see that the Apple and Cars options are removed.

Conclusion

To remove values from select list based on condition with JavaScript, we can watch the selected value of the drop down.

Then we can remove the values accordingly.

Sometimes, we want to validate dates in format MM-DD-YYYY with JavaScript.

In this article, we’ll look at how to validate dates in format MM-DD-YYYY with JavaScript.

How to validate dates in format MM-DD-YYYY with JavaScript?

To validate dates in format MM-DD-YYYY with JavaScript, we can use a regex to get the date parts.

And then we can compare the parts when we put them into the Date constructor to create a new date from them.

For instance, we write:

const isValidDate = (date) => {
  const matches = /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/.exec(date);
  if (matches === null) {
    return false;
  }
  const [_, m, d, y] = matches
  const composedDate = new Date(+y, +m - 1, +d);
  return composedDate.getDate() === +d &&
    composedDate.getMonth() === +m - 1 &&
    composedDate.getFullYear() === +y;
}
console.log(isValidDate('10-12-1961'));

We use the /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/ regex to extract the date parts with the exec method.

Then we destructure the matches and assign the month to m, day to d, and year to y.

Next, we create a new date object with the Date constructor with the date parts.

We’ve to subtract 1 from m to conform with with the Date constructor accepts as the month value.

Finally, we compare the date, month and year from the composedDate object with the values extracted from the regex.

We use the unary + operator to convert each value to numbers.

Therefore, the console log should log true.

Conclusion

To validate dates in format MM-DD-YYYY with JavaScript, we can use a regex to get the date parts.

And then we can compare the parts when we put them into the Date constructor to create a new date from them.

Sometimes, we want to add a dialog box with jQuery and make it show more than once.

In this article, we’ll look at how to add a dialog box with jQuery and make it show more than once.

How to add a dialog box with jQuery and make it show more than once?

To add a dialog box with jQuery and make it show more than once, we can use the jQuery UI’s dialog method with the modal option set to true.

For instance, we write:

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.css" />

<button>
  show
</button>

<div id="dialog" title="Basic dialog">
  <p>hello world.</p>
</div>

We add the show button and a div for the dialog.

Then we write:

$(() => {
  $("#dialog").hide()

  $('button').click(() => {
    $("#dialog")
      .dialog({
        modal: true,
      })
  })
});

We select the dialog div with $("#dialog").

And we call hide on it to hide it initially.

Then we select the button with $('button').

And we call click on it with a callback that calls dialog with an object with modal set to true.

Now when we click the button, we see the dialog displayed. And we can close it with the ‘x’ button and click show to open it again.

Conclusion

To add a dialog box with jQuery and make it show more than once, we can use the jQuery UI’s dialog method with the modal option set to true.

Sometimes, we want to check which element has been clicked with jQuery.

In this article, we’ll look at how to check which element has been clicked with jQuery.

How to check which element has been clicked with jQuery?

To check which element has been clicked with jQuery, we can add a click event listener to the body element.

Then we can check which element is clicked inside the click event handler with the is method.

For instance, we write:

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>

<p>
  foo
</p>

<div>
  bar
</div>

<section>
  baz
</section>

to add a few elements into the page.

Then we write:

$('body').click((e) => {
  const target = $(e.target);
  if (target.is('p')) {
    console.log('p clicked')
  } else if (target.is('div')) {
    console.log('div clicked')
  } else if (target.is('section')) {
    console.log('section clicked')
  }
});

We select the body element with $.

Then we call click on it with a callback that gets the clicked element with the e.target property.

Then we check for what’s clicked with the is method called with the selector we’re checking for.

Therefore, when we click on different elements, we should see different text logged.

Conclusion

To check which element has been clicked with jQuery, we can add a click event listener to the body element.

Then we can check which element is clicked inside the click event handler with the is method.