Learn JavaScript

none — a dragged item cannot be dropped here. This is the default value for everything except text boxes.

Each of these values causes a different cursor to be displayed when an item is dragged over the drop target.

None, it is up to you to actually cause the actions indicated by the cursor. In other words,

What is the only thing you get for free with these values?

You must set it in the ondragenter event handler for the drop target.

What must you set for dropeffect property to be able to do anything worthwhile?

Indicates which dropeffect is allowed for the dragged item.

uninitialized — no action has been set for the dragged item.

Inside the ondragstart event handler.

what must you do to allow a user to move text from a text box into a <div>.

Because the default behavior for the drop event on a <div> is to do nothing.

The text is automatically removed from the text box.

It is then up to you to insert it into the <div> to finish the action.

The text in the text box would not automatically be removed.

Only after a section has been highlighted,

When are images and links draggable

What does html5 have on all elements indicating if the element can be dragged?

All html images and links have draggable automatically set to true. Everything else has a default value of false.

Give an example of setting draggable on, or off.

what two media-related elements does html5 introduces to enable cross-browser audio and video embedding into a browser baseline without any plug -ins?

easily embed media files into a page and provide javascript hooks into common functionality.

What are the available elements for audio an video?

Each of these elements requires, at a minimum, the src attribute indicating the media file to load.

you can also specify width and height attributes to indicate the intended dimensions of the video player and a poster attribute that is an image uri to display while the video content is being

The controls attribute, if present, indicates that the browser should display a ui enabling the user to interact directly with the media.

considered alternate content to display if the media player is unavailable.

How can you provide for browsers that do not support specific media formats?

Omit the src attribute from the element and instead include one or more <source> elements.

Autoplay boolean gets or sets the autoplay flag.

What are the additional media events and when do they fire?

.JSON can be passed directly to _______ method and doesn't require the creation of a _______.

Simple values( String, number, Boolean, and null but not undefined), Objects and Arrays.

one does not! There are no variables, functions, or object instances in JSON.

JSON is all about representing what?

JSON strings must use what in order to be valid?

JSON's rise to popularity may have been because the data could be _______ into a usable object in JavaScript

The JSON object has two methods:_______ & _______

In simple usage, _______serializes JavaScript objects into a JSON what?

The _______ method handles custom JSON serialization beyond what JSON.stringify() can handle.

JSON.stringify() accepts two optional additional arguments for filtering & indentation. Likewise JSON.parse() accepts an optional additional argument called a _______ function which is a function called on each key-value pair.

If the results of the function with branching is the same for every instance it is called, the code is overwritten for subsequent calls of the function so that branching occurs only once(i.e, the f…

There are two ways: 1) manipulate the function the first time the code is called the function is overwritten with another function so that future function calls need not go through the execution branch…

also called partial function application, functions are created with one or more arguments already set.

What mechanism in ECMAScript5 is used to avoid one object overwriting another object's code, i.e. create Tamper-Proof Objects?

By default, JavaScript is extensible additional properties and methods can be added to an object. How can objects be made Nonextensible? What method is used to determine whether an object is extensible?

Next level of object protection: Objects aren't extensible and existing members have their [[Configurable]] attribute set to false. properties and methods cannot be deleted. data properties cannot be altered. Properties values can be changed.

What is the method to seal an object?

Object.isSealed(): Method to determine whether an object is sealed or not sealed.

the strictest type of tamper-proof object. aren't extensible and are sealed, and also data properties have their [[Writable]] attribute set to false.

What method is used to determine if an object is frozen?

What method(s) are used to determine if an object is frozen?

main library objects. Freezing prevents accidental or intensional changes to the library.

Do isSealed () and isExtensible() operate on frozen objects? If so, what are the return values? If not, why not?

What methods are used to schedule execution of code in JavaScript?

It's not possible to secure an event to occur at a specific time because JavaScript runs in a single-threaded time environment. The browser prioritizes the jobs in a queue. The event gets executed as …

F: the specified interval indicates when the timer's code is added to the queue not when execution occurs. Execution occurs when the processor is idle.

For the purpose of limiting long-running scripts when it runs longer than a certain amount of time or more than certain number of statements.

With arrays, a technique of processing arrays in small chunks with timers when the processing can be done asynchronously, or processed nonsequentially.

It's is best to split a job into smaller ones for functions taking over 50 milliseconds to complete.

It is the basic idea of not allowing certain code to execute without a break.

observer pattern. The it is made up of two types of objects: subject and observer. The subject is responsible for publishing events. The observer simply observes the subject by subscribing to these events.

Custom events create objects that manage events, allowing for others to listen to those events.

image or multiple images that shadows mouse pointer movements on the page for drag and drop functionality.

What property and two events can be used for offline detection?

A manifest file lists the files that the browser should download and cache in the application cache.

What property can be used to get and set cookies? What format should be used when setting the property?

For every request from the browser, every cookie matching the requested domain and path is sent in the header of the request. The larger the cookie information, the longer it will take to complete the request to the server.

What are the methods of the Storage type? How can you determine the number of name-value pairs in the Storage object?

How long does the sessionStorage object store data?

globalStorage allows you to specify the domains which will have access to the data, while localStorage only gives access to data set from the domain using the same protocol on the same port.