Javascript 1: Language Fundamentals (chapter 8)

local scope or function scope

variables defined in local scope are only available within the function

fail safe design

when a plan fails then the system's design will still work

text-based client

widely deployed on web servers, often accessed using a command line interface

inline javascript

including Javascript code directly within certain HTML attributes

Client-side scripting

-displays the pages given by the server to the user -code written needs to ensure that it can make interactive webpages from the source code sent by the server -the client interact with local storage (such as cookies) -programming usually done with JavaScript

the disadvantages of client side scripting

-no guaranteed the client has Javascript enabled -JScript is not fault tolerant. -What works in one browser, may generate an error in another -Javascript-heavy web applications can be complicated to debug/maintain.

the advantages of client side scripting

-processing can be off-loaded from server to client machines; reducing load on server -browser can respond more rapidly to user events - JScript can interact w/downloaded HTML in a way the server cannot

function expression

1 var bindingName = function actualName () { 2 //... 3 };

browser plug-in

A software add-on that extends functionality and capabilities of the browser

AJAX

Asynchronous JavaScript and XML, which permits Web information to be processed without reloading a page.

console.log()

Displays a string and/or variable values in the the browser's javascript console

for loop

Loops that have a predetermined beginning, end, and increment (step interval). initialization, condition, and post loop operation in one statement.

applet

Small Java application that performs relatively small tasks

global scope

variables defined in global scope are available globally, within every function.. any code written outside of a function

dot notation

Used to reference an object in an imported module or access the properties or methods of an object

reference types

a basic data type in Javascript. usually referred to as objects.

anonymous function

a set of related statements with no name assigned to it.

push() method

add an item to the end of an existing array

external Javascript files

also called libraries. typically contain function definitions, data definitions, and other blocks of JS codes best recommended to place these links in head or body element

browser extension

also extend functionality but not used to process downloaded content

method

an action that an object can perform

Javascript

an object-oriented computer programming language commonly used to create interactive effects within web browsers. (clients-side scripting language) Dynamically typed (weakly typed); variables can be easily converted from one data type to another.

primitive types

another basic data type that are non objects, simple types can be used as if they are objects. represent simple forms of data.

web crawler

client running on behalf of a search engine to download sites

while loop

condition is tested at the beginning of the loop. pretest loop

do...while loop

condition is tested at the end of each iteration of the loop. posttest loop

scope

context in which code is being executed

arrays

data structure that allows programmers to collect numbers of relative elements together in a single variable. they're zero indexed, first element is accessed as index 0

function declaration

declaration of a function, including its name, argument types, and return type.

functions

defined by using reserved word "function" and then the function name and parameter does not require a return type nor does the parameter requires type specifications. can be stored in a variable or passed as a parameter to another function

prototypes

essential syntax mechanism in Javascript; used to make JS behave more like an object oriented language enables you to extend existing objects

callback function

function that is passed to another function. the function that receives the function parameter is able to call the passed in function at some future point.

objects

in Javascript they are prototype based rather class based (functions in JS are also objects). collection of named values.

JavaScript framework

libraries of JS functions and objects

alert()

makes the browser show a pop-up to the user

identifier

must begin with a $ or _ or any character within one of several Unicode categories

built-in objects

object, function, boolean, error, number, math, date, string, regexp

document.write()

outputs markup content to a web page

property

piece of data that belongs to an object

embedded javascript

placing Javascript within a script element

minification

process of removing unnecessary characters such as extra spaces and comments in order to reduce the size of the code and reduce time it takes to download

pop() method

remove the last element from an array

ECMAScript

superset and subset of the Javascript programming language

variables

they are objects and they have properties and methods. dynamically typed and do not have to declare the type of a variable before use. should always be defined using var keyword. Without it will give a variable global scope.

Javascript Object Notation (JSON)

used as a language independent data interchange format analogous in use to XML.

conditional assignment operator

used to assign values based on a condition

object literal notation

used to define an array