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prevent-listener

The prevent-listener snippet prevents the addition of event listeners. 
You can use prevent-listener by wrapping EventTarget.prototype.addEventListener and not allowing listeners to be added for certain event types.
Parameters
Name
Description
Mandatory
type
A pattern that matches the type(s) of events you want to prevent. If the string starts and ends with a slash (/), the text in between is treated as a regular expression.
Yes
handler
A pattern that matches the event handler's declaration. If the string starts and ends with a slash (/), the text in between is treated as a regular expression.
No
selector
The CSS selector that the event target must match. If the event target is not an HTML element, the event handler is added.
No
Filter examples
The following table lists examples that use the abort-on-iframe-property-write snippet:
Filter
Result
prevent-listener click
No event listener will be added for click events.
prevent-listener click console div
No click event listener will be added on div elements whose handler matches console.  
​
For example, these listeners won't be added:
 window.addEventListener("click", ()=>console.log("click"))

document.body.addEventListener("click", ()=>console.log("click"))

But this listener would be added:

omeDiv.addEventListener("click", ()=>console.log("click"))
prevent-listener click console
No listener will be added for click events whose handler matches console.

For example, these listeners won't be added:

 someElement.addEventListener("click", () => console.log("click")) 

But these listeners would be added:

someElement.addEventListener("click", () => alert("click"))
Debugging
The following table contains messages you'll find useful during debugging:
Message
When the message occurs
Definition
DEBUG [prevent] Wrapped addEventListener
After wrapping
Displayed after addEventListener has been wrapped.
DEBUG [prevent] was successful

DEBUG [prevent] type: actualType matching providedType 

DEBUG [prevent]handler: actualHandler

DEBUG [prevent] matching providedHandler 

DEBUG [prevent] on element actualElement matching selector

DEBUG [prevent] was prevented from being added
Each time a listener is prevented from being added
This is a group of logs containing detailed information about the event type and its handler. They're displayed each time we prevent a listener from being added.

If the optional handler or selector parameter was omitted, the corresponding log(s) will be skipped.

Name	Description	Mandatory
type	A pattern that matches the type(s) of events you want to prevent. If the string starts and ends with a slash (`/`), the text in between is treated as a regular expression.	Yes
handler	A pattern that matches the event handler's declaration. If the string starts and ends with a slash (`/`), the text in between is treated as a regular expression.	No
selector	The CSS selector that the event target must match. If the event target is not an HTML element, the event handler is added.	No

Filter	Result
prevent-listener click	No event listener will be added for click events.
prevent-listener click console div	No click event listener will be added on div elements whose handler matches console. For example, these listeners won't be added: `window.addEventListener("click", ()=>console.log("click"))` `document.body.addEventListener("click", ()=>console.log("click"))` But this listener would be added: `omeDiv.addEventListener("click", ()=>console.log("click"))`
prevent-listener click console	No listener will be added for click events whose handler matches console. For example, these listeners won't be added: `someElement.addEventListener("click", () => console.log("click"))` But these listeners would be added: `someElement.addEventListener("click", () => alert("click"))`

Message	When the message occurs	Definition
`DEBUG [prevent] Wrapped addEventListener`	After wrapping	Displayed after `addEventListener` has been wrapped.
`DEBUG [prevent] was successful` `DEBUG [prevent] type: actualType matching providedType` `DEBUG [prevent]handler: actualHandler` `DEBUG [prevent] matching providedHandler` `DEBUG [prevent] on element actualElement matching selector` `DEBUG [prevent] was prevented from being added`	Each time a listener is prevented from being added	This is a group of logs containing detailed information about the event type and its handler. They're displayed each time we prevent a listener from being added. If the optional handler or selector parameter was omitted, the corresponding log(s) will be skipped.

Last modified 9mo ago