Javascript – Bookmarklet – grabbing videos from other sites

As of jQuery 1.7 you should use jQuery.fn.on with the selector parameter filled:

$(staticAncestors).on(eventName, dynamicChild, function() {});

Explanation:

This is called event delegation and works as followed. The event is attached to a static parent (staticAncestors) of the element that should be handled. This jQuery handler is triggered every time the event triggers on this element or one of the descendant elements. The handler then checks if the element that triggered the event matches your selector (dynamicChild). When there is a match then your custom handler function is executed.

Prior to this, the recommended approach was to use live():

$(selector).live( eventName, function(){} );

However, live() was deprecated in 1.7 in favour of on(), and completely removed in 1.9. The live() signature:

$(selector).live( eventName, function(){} );

... can be replaced with the following on() signature:

$(document).on( eventName, selector, function(){} );

For example, if your page was dynamically creating elements with the class name dosomething you would bind the event to a parent which already exists (this is the nub of the problem here, you need something that exists to bind to, don't bind to the dynamic content), this can be (and the easiest option) is document. Though bear in mind document may not be the most efficient option.

$(document).on('mouseover mouseout', '.dosomething', function(){
    // what you want to happen when mouseover and mouseout 
    // occurs on elements that match '.dosomething'
});

Any parent that exists at the time the event is bound is fine. For example

$('.buttons').on('click', 'button', function(){
    // do something here
});

would apply to

<div class="buttons">
    <!-- <button>s that are generated dynamically and added here -->
</div>

To remove a property from an object (mutating the object), you can do it like this:

delete myObject.regex;
// or,
delete myObject['regex'];
// or,
var prop = "regex";
delete myObject[prop];

Demo

var myObject = {
    "ircEvent": "PRIVMSG",
    "method": "newURI",
    "regex": "^http://.*"
};
delete myObject.regex;

console.log(myObject);

For anyone interested in reading more about it, Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog, Understanding delete. It is highly recommended.

If you'd like a new object with all the keys of the original except some, you could use the destructuring.

Demo

let myObject = {
  "ircEvent": "PRIVMSG",
  "method": "newURI",
  "regex": "^http://.*"
};

const {regex, ...newObj} = myObject;

console.log(newObj);   // has no 'regex' key
console.log(myObject); // remains unchanged