How Can I Pass Arguments to an addEventListener Function?

How to Pass Arguments to addEventListener Listener Functions

In a scenario where we want to pass arguments to an event listener function, we might encounter a situation where the argument is inaccessible within the function. This can occur when we assign a variable to the function, like this:

var someVar = some_other_function();
someObj.addEventListener("click", function(){
    some_function(someVar);
}, false);

Here, the issue is that the value of someVar is not available within the event listener's function.

A Better Approach: Using the Event Target's Parameter

To resolve this, we can leverage the target attribute of the event object to retrieve the parameters passed to the listener function. Consider this example:

const someInput = document.querySelector('button');
someInput.addEventListener('click', myFunc, false);
someInput.myParam = 'This is my parameter';

function myFunc(evt)
{
    window.alert(evt.currentTarget.myParam);
}

In this modified code:

• We assign our parameter ('This is my parameter') to the myParam property of the input element.
• Our myFunc function is defined outside of the event listener's scope.
• When the input element is clicked, the myFunc function is invoked.
• Within the myFunc function, we can access our parameter via evt.currentTarget.myParam.

This approach effectively allows us to pass arguments to our event listener function without encountering the original issue.

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