JavaScript and jQuery basics

JavaScript and jQuery basics

Multiple Select

Which of the following declare and assign a variable correctly in JavaScript? (Choose 2)

• var x = 5;

• value = var 10;

• variable = "Hello World";

• let name = "John";

Multiple Select

By accessing the DOM, which of the following can JavaScript do? (Choose 3)

• Change all the elements on the page

• Add or remove HTML elements and attributes

• Read or write files on the user's system

• Permanently modify the website's files

• Change all the CSS on the page

Multiple Choice

Which of the following will create an object?

• { }

• [ ]

• < >

• ( )

Multiple Choice

Which of the following will create an array?

• { }

• [ ]

• < >

• ( )

Multiple Choice

Which of the following invokes a function?

• { }

• [ ]

• < >

• ( )

Multiple Choice

In JavaScript, all variables must be identified with unique names.

• True

• False

Variables in JavaScript

• The "identifier" or name of a variable in JavaScript will uniquely identify it

• This means that when you create a variable, you need to make sure the name is unique in the current scope or you may end up overwriting the original variable

Multiple Select

Which of the following will create a function in JavaScript? (Choose 3)

• function(parameters) { ... }

• function name(parameters) { ... }

• name(parameters) { ... }

• function { (parameters) ... }

• (parameters) => { ... }

Multiple Choice

What does DOM stand for?

• Document Ordered Model

• Data Object Model

• Document Object Matter

• Document Object Model

Multiple Choice

What is the file type of external JavaScript files?

• .java

• .js

• .script

• .jsp

Multiple Select

Which of the following values are "truthy"?

• "false"

• 0

• null

• {} (empty object)

Converting values to booleans

• Values in JavaScript are either "truthy" or "falsy"

• This just means that when converted into a boolean, they will be coverted to true or false, respectively.

• Some "truthy" values are: Any object, any function, numbers that are not 0, any non-empty string

• Some "falsy" values are: null, undefined, 0, "" (the empty string)

• This can, in some cases, be used to check if a value was set correctly or if a variable exists

Multiple Select

Which of the following rules must variable names (identifiers) obey? (Choose 2)

• Identifiers must not contain numbers

• Identifiers must not start with a number

• Identifiers can only contain letters, digits, _ and $

• Identifiers must start with a letter

Multiple Choice

What is the name of the variable in the following JavaScript code?

function greet() {

let name = "John";

console.log("Hello " + name);

}

• greet

• John

• name

• log

Multiple Choice

What does AJAX stand for?

• Asynchronous JavaScript and XML

• Asynchronous JSON and XML

• Automated JavaScript and XML

• Automated JSON and XML

Multiple Choice

What does JSON stand for?

• JavaScript Ordered Notation

• JavaScript Object Notation

• JavaScript Object Network

• JavaScript Ordered Network

Multiple Select

jQuery can select elements based on which of the following? (Choose 4)

• Classes

• Attributes

• Type

• Location

• Relationship

Multiple Select

Which of these are advantages of using jQuery? (Choose 3)

• Consistent and cross-browser way of working with the DOM

• Simplified code for accessing the DOM

• Faster performance when modifying the DOM

• Quicker loading times

• Using plugins to extend website functionality

Multiple Choice

Which of the following is a shortcut to access jQuery?

• _

• $

• jQ

• &

Multiple Choice

When using jQuery's methods which modify elements, you can only select one element at a time

• True

• False

Multiple Choice

What will the selector ":even" select in jQuery?

• Every element of type "even"

• Every element in an even position within its parent

• Every element that contains an even number

• Every other element

Special selectors in jQuery

• :even will select any elements that are in an even position within their parent (useful for tables)

• :parent will select any element that is a parent (i.e. has some element within it)

• :hidden will select any element that is hidden (usually with jQuery's hide method)

• :focus will select the element that currently has focus (usually useful for input elements, buttons and links)

• There are many more, you can find them in jQuery's documentation

Multiple Choice

What does the following jQuery code do?

$(function() {

...

}

• Runs the given function when the user tries to leave the page

• Runs the given function immediately, but with jQuery

• Adds the given function to jQuery

• Runs the given function before the page has loaded

• Runs the given function when the page is fully loaded