Category: JavaScript Answers

Categories
JavaScript Answers

How to expose IFrame’s DOM using jQuery?

Labrador retriever puppy walking on green grass

Exposing an iFrame’s DOM using jQuery is not directly possible due to security restrictions.

This is because of the Same Origin Policy, which prevents scripts from accessing the contents of an iFrame if it’s loaded from a different domain, protocol, or port than the parent page.

However, if the iFrame source is from the same origin as the parent page, you can manipulate its DOM using jQuery.

To do this we can write:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Parent Page</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
$(document).ready(function() {
    // Accessing the iFrame's content
    var iframeDocument = $('#myIframe').contents();

    // Manipulate the iFrame's content using jQuery
    iframeDocument.find('#iframeContent').css('color', 'red');
});
</script>
</head>
<body>
<iframe id="myIframe" src="iframe-content.html"></iframe>
</body>
</html>

In this example, we’re loading an iFrame with the id “myIframe” and setting its source to “iframe-content.html”. This source is assumed to be on the same origin as the parent page.

Inside the jQuery code, we’re accessing the iFrame’s content using $('#myIframe').contents(). This gives us access to the iFrame’s document and allows us to manipulate its DOM.

We then use standard jQuery methods to manipulate the iFrame’s content. In this case, we’re changing the color of an element with the id “iframeContent” inside the iFrame.

Remember, you can only access the iFrame’s content if it’s from the same origin as the parent page.

If the iFrame is from a different origin, you won’t be able to access its DOM due to security restrictions.

Categories
JavaScript Answers

How to select all checkboxes with jQuery?

Labrador retriever puppy walking on green grass

To select all checkboxes using jQuery, you can use the prop() method to set the checked property of each checkbox to true.

To do this we write

<!-- HTML checkboxes -->
<input type="checkbox" class="checkbox">
<input type="checkbox" class="checkbox">
<input type="checkbox" class="checkbox">
<input type="checkbox" class="checkbox">

<!-- jQuery code to select all checkboxes -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
$(document).ready(function() {
    $('#selectAll').click(function(event) {   
        // Iterate through each checkbox
        $('.checkbox').each(function() {
            // Set checked property to true
            $(this).prop('checked', true);
        });
    });
});
</script>

In this code, each checkbox has a class of “checkbox” to select them collectively.

There’s a button (or any element with the id “selectAll”) that, when clicked, will trigger the jQuery code.

Inside the jQuery code, the each() function iterates through each checkbox with the class “checkbox”.

For each checkbox, the prop() function sets the checked property to true, effectively selecting all checkboxes.

This code will select all checkboxes when the “Select All” button (or any element with the id “selectAll”) is clicked.

Categories
JavaScript Answers

How to restrict a text field to numbers only with JavaScript?

Labrador retriever puppy walking on green grass

To restrict a text field to accept only numbers using JavaScript, you can use the onkeypress event to validate each key pressed by the user.

For example we write

<input type="text" id="numberField" onkeypress="return isNumberKey(event)">

to an input.

And here’s the JavaScript function to enforce the restriction:

function isNumberKey(evt) {
  var charCode = (evt.which) ? evt.which : event.keyCode;
  if (charCode > 31 && (charCode < 48 || charCode > 57)) {
    return false;
  }
  return true;
}

In this code, the isNumberKey() function checks if the key pressed is a number.

It uses event.which or event.keyCode to determine the key code of the pressed key.

If the key code is not within the range of numbers (48 to 57 for digits 0-9), it returns false, preventing the input.

This method will ensure that only numeric characters are allowed in the text field.

However, keep in mind that users can still paste non-numeric text into the field unless you additionally handle the onpaste event to prevent this.

Categories
JavaScript Answers

How to get relative time 24 hours ago as time with JavaScript?

Labrador retriever puppy walking on green grass

To get the relative time 24 hours ago using JavaScript, you can create a new Date object for the current time and then subtract 24 hours from it.

To do this, we can write

// Get the current time
var currentTime = new Date();

// Subtract 24 hours (24 * 60 * 60 * 1000 milliseconds)
var twentyFourHoursAgo = new Date(currentTime - 24 * 60 * 60 * 1000);

// Format the date to display
var formattedTime = twentyFourHoursAgo.toLocaleString();

console.log("24 hours ago:", formattedTime);

In this code, we create a new Date object called currentTime, representing the current time.

We then subtract 24 hours from currentTime by creating a new Date object called twentyFourHoursAgo using the milliseconds equivalent of 24 hours.

Finally, we format the twentyFourHoursAgo date object into a human-readable string using the toLocaleString() method.

This will give you the date and time 24 hours ago relative to the current time. You can adjust the formatting to suit your needs.

Categories
JavaScript Answers

How to manually add some items with Selectize.js?

Labrador retriever puppy walking on green grass

To manually add items to a Selectize.js dropdown, you can use the addOption() method.

To do this we can try the following.

1. Include Selectize.js

Make sure you have included Selectize.js in your HTML file. You can either download it and include it locally or use a CDN.

<link rel="stylesheet" href="path/to/selectize.css">
<script src="path/to/selectize.js"></script>

2. Create HTML Select Element

Create a select element in your HTML file and give it an ID.

<select id="mySelect"></select>

3. Initialize Selectize

Use JavaScript to initialize the Selectize plugin on your select element.

var mySelect = $('#mySelect').selectize({
    create: true,
    sortField: 'text'
});

4. Add Items Programmatically

You can then add items to the select element using the addOption() method.

var selectize = mySelect[0].selectize;

// Add items manually
selectize.addOption({value: '1', text: 'Option 1'});
selectize.addOption({value: '2', text: 'Option 2'});

You can call addOption() as many times as needed to add multiple items.

5. Trigger Dropdown Refresh

After adding options, you might need to refresh the dropdown to reflect the changes. You can do this by calling the refreshOptions() method.

selectize.refreshOptions();

That’s it! You’ve now manually added items to a Selectize.js dropdown. This can be useful when you want to dynamically populate the dropdown based on user actions or data from an external source.