Question

How can i handle mouse wheel event in javascript, part of chrome extension.

// MAIN
if (document.addEventListener) {
    document.addEventListener("mousewheel", wheelHandler, false);
} else {
}
// END MAIN

function wheelHandler(e) {
    alert("activated");
}

Activated alert newer happens, why is that?

Answer 1

Chrome extensions require a manifest.json file which has the content settings for the extension. In this file you are able to identify content scripts that are run with the extension.

As an example (the first 3 fields here are required):

{
    "name": "",
    "version": "",
    "manifest_version": 2,
    "content_scripts":
    [{
        "matches": ["url patterns here...."]
        "js": ["jquery-1.8.3.js", "main.js"],
        "run_at": "document_idle"
    ]}, 
    .....
    .....
    "permissions":
    [
        "some permissions...."
    ]
}