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Error: Permission denied to access property 'target' in JavaScript
"Error ? Permission denied to access property 'target'" is a common error message that occurs when working with JavaScript, especially when attempting to access the target property of an event object. This error occurs when a script tries to access a property or method of an object that it does not have permission to access. In this tutorial, we will discuss the causes of this error and how to fix it.
Understanding the Error
The "Error ? Permission denied to access property 'target'" is typically caused by the use of the target property of an event object in a context where the script does not have permission to access it. The target property of an event object refers to the element on which the event occurred. For example, if a user clicks on a button, the target property of the click event would refer to the button element.
The error occurs when the script tries to access the target property from an object, like a window object, where it does not have permission to access it. This can happen when the script is running in a different context or if it has been loaded from a different origin.
Common Causes
There are several common causes of the "Error: Permission denied to access property 'target'" error:
Cross-Origin Scripting ? This error can occur when a script is loaded from a different origin than the page trying to access it. This is a security feature in web browsers to prevent malicious scripts from accessing sensitive information.
Incorrect Event Handling ? This error can occur when a script tries to access the target property of an event object before it has been fully initialized.
Object is not Event object ? This error can occur when a script tries to access the target property of an object that is not an event object. For example, trying to access the target property of a window object will cause this error.
Example: Cross-Origin Access Issue
<html>
<head>
<title>Cross-Origin Access Example</title>
</head>
<body>
<div id="print"></div>
<script>
// This will cause a cross-origin error
var iframe = document.createElement("iframe");
iframe.src = "https://www.tutorialspoint.com";
document.body.appendChild(iframe);
try {
// This will throw permission denied error
var target = iframe.contentWindow.document.querySelector("p");
document.getElementById("print").innerHTML = "Success: " + target;
} catch (error) {
document.getElementById("print").innerHTML = "Error: " + error.message;
}
</script>
</body>
</html>
Solutions to Fix the Error
The solution depends on the cause of the error. Here are common approaches:
Check the Origin ? If the error is caused by cross-origin scripting, verify that the script and page have the same origin using document.location.origin.
Use Correct Event Handlers ? Instead of accessing target properties prematurely, use proper event handlers and ensure the event object is fully initialized.
Verify Object Type ? Ensure you're accessing the target property on an actual event object, not other object types like window or document.
Use event.currentTarget ? As an alternative, use event.currentTarget instead of event.target when using event delegation. CurrentTarget always refers to the element with the event listener attached.
Using Try-Catch for Error Handling
To handle situations where this error might occur, use a try-catch block:
function handleEvent(event) {
try {
// Attempt to access the target property
console.log("Target element:", event.target);
console.log("Target tagName:", event.target.tagName);
} catch (error) {
console.log("Error accessing target:", error.message);
// Use currentTarget as fallback
console.log("Using currentTarget instead:", event.currentTarget);
}
}
// Example usage
document.addEventListener('click', handleEvent);
Target element: [object HTMLElement] Target tagName: BUTTON
Same-Origin Policy Example
The most common scenario involves the Same-Origin Policy, where scripts can only access properties from the same origin:
// This will work - same origin
try {
var localTarget = document.getElementById('myButton');
console.log(localTarget.tagName); // Works fine
} catch (error) {
console.log("Error:", error.message);
}
// This will fail - cross origin
try {
var crossOriginWindow = window.open('https://example.com');
var crossTarget = crossOriginWindow.document.body; // Permission denied
} catch (error) {
console.log("Cross-origin error:", error.message);
}
Conclusion
The "Error: Permission denied to access property 'target'" error is primarily a security measure enforced by browsers. Always verify object types, check origins, and use try-catch blocks to handle these errors gracefully in your JavaScript applications.
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