JavaScript 2 Flashcards
1
Q
- What is JSON?
A
- JavaScript Object Notation, A text-based data format following JavaScript object syntax, it exists as a string
2
Q
- What are serialization and deserialization?
A
- Converting a native object to a string is serialization while converting a a string to a native object is called deserialization
3
Q
- Why are serialization and deserialization useful?
A
- To transmit data across a network and to receive it from the network.
*
4
Q
How do you serialize a data structure into a JSON string using JavaScript?
A
- JSON.stringify();
5
Q
- How do you deserialize a JSON string into a data structure using JavaScript?
A
- JSON.parse();
6
Q
- How to you store data inlocalStorage?
A
- localStorage.setItem();
7
Q
- How to you retrieve data fromlocalStorage?
A
- localStorage.getItem();
8
Q
- What data type canlocalStoragesave in the browser?
A
- Strings
9
Q
- When does the’beforeunload’event fire on thewindowobject?
A
- It fires a window before everything is unloaded to cancel the event before the browser unloads all the information stored.
10
Q
- What DOM element property tells you what type of element it is?
A
- . .tagName;
11
Q
- Describe methoddefinitionsyntax (structure).
A
- Stored in an object a property and anonymous function definition
12
Q
- Describe methodcallsyntax (structure)
A
- .method();
13
Q
- What is thedefining characteristicof Object-Oriented Programming?
.
A
- objects can contain both data (as properties) and behavior (as methods).
14
Q
- What are the four “principles” of Object-Oriented Programming?
A
- Abstraction, inheritance, encapsulation and polymorphism
15
Q
- What is “abstraction”?
A
- Being able to work with complex things in simple ways. Like a light switch or automatic transmission.
16
Q
- What does API stand for?
A
- Application programming Interface.
17
Q
- What is the purpose of an API?
A
- To give programmers a way to interact with a system in a simplified consistent fashio
18
Q
- What isthisin JavaScript?
A
- This implicit parameter of every javascript function that contains
a reference to the object is bring called from
19
Q
- What does it mean to say thatthisis an “implicit parameter”?
A
- Its always available we don’t need to write it
20
Q
- Whenis the value ofthisdetermined in a function;call timeordefinition time?
A
- Call
21
Q
- How can you tell what the value ofthiswill be for a particular function or methoddefinition?
A
- It won’t be anything
22
Q
- How can you tell what the value ofthisis for a particular function or methodcall?
.
A
- its the object next to the method
23
Q
- What kind of inheritance does the JavaScript programming language use?
A
- Prototypal inheritance
24
Q
- What is a prototype in JavaScript?
A
a JavaScript prototype is simply an object that contains properties and (predominantly) methods that can be used by other objects.
25
* How is it possible to call methods on strings, arrays, and numbers even though those methods don't actually exist on strings, arrays, and numbers?
* They inherit them from the prototype object
26
* If an object does not have it's own property or method by a given key, where does JavaScript look for it?
* Prototype
27
* What does the new operator do?
* Creates a blank plain object and adds a property to the new object _proto_ , it binds the new created object as the this context and return this if the function doesn’t return an object
28
* What property of JavaScript functions can store shared behavior for instances created with new?
* Proto
29
* What does the instanceof operator do?
* Tests to see if the prototype property of a constructor appears in the prototype chain of an object, it returns a boolean
30
* What is a "callback" function?
* A function definition stored as an argument
31
* Besides adding an event listener callback function to an element or the document, what is one way to delay the execution of a JavaScript function until some point in the future?
* setTimeout()
32
* How can you set up a function to be called repeatedly without using a loop?
* setInterval()
33
* What is the default time delay if you omit the delay parameter from setTimeout() or setInterval()?
* 0
34
* What do setTimeout() and setInterval() return?
* A positive integer value to identify the timer
