M7 JavaScript Flashcards by Jessica Arboleda

Lightweight, cross-platform, single-threaded, and interpreted programming language for creating dynamic and interactive web content

JavaScript

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JavaScript:
How does it function on the client side?

It runs on the user’s browser alongside HTML and CSS to enable user interaction

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JavaScript: how does it function on the server side?

It functions by managing databases, file systems, and security

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JavaScript: It enables a wide array of applications beyond the web. What are those?

Mobile app development
Game development
IoT
Real-time systems

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It was sometimes dismissed as a “toy language” with limited capabilities

JavaScript

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What you can build with JavaScript (examples)

Full-blown web or mobile apps
Real-time networking services (like chats and video streaming)
Command-line tools
games

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What browsers have that let it execute JavaScript code

JavaScript Engine

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Examples of JavaScript engines

SpiderMonkey (firefox)
v8 (chrome)

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A C++ program that has chrome’s JavaScript engine (v8) embedded in it. It lets you run JavaScript outside a browser; lets you build the backend for web and mobile applications

Node

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The standard for JavaScript

ECMAScript

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Official name of JavaScript

ECMAScript

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JavaScript lives between __ tags

script

(

and

)

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Old example of a tag containing JavaScript (inline)

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Where are scripts usually placed?

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When scripts are put here, it runs before the page content loads. It might slow the rest of the page down

Scripts put in <head>

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When script is put here, it runs as the page loads. It makes things snappier for users

Script in the <body>

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Form of JavaScript that makes the code reusable and faster thanks to browser caching

External JavaScript

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How do you reference external scripts

Full URLs
-
Relative paths
No path

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There should be no script tags in JavaScript files

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JavaScript’s ways of displaying data

innerHTML()
document.write()
alert()
console.log()

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A way JavaScript displays data wherein it finds an existing element by its ID and updates the content

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innerHTML()

Syntax of innerHTML() when used with a button and getting element id.

In other words. What would be the syntax if u were to use a button to replace a paragraph?

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[Button name]

</button>

This code says:
“When someone clicks this button, go find the HTML element whose id equals whatever is inside those brackets ([id]) and replace its inner HTML (that’s the content inside the element) with whatever’s in [new replacement].”

Remember. The innerHTML part is necessary so it actually replaces the contents of the id’d element. If we remove that, nothing will happen.

A way of displaying data in Javascript that outputs it directly into the HTML document

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document.write()

What do you put in the parenthesis in document.write()?

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The output you want to display in the document

Example:
…

<script>
document.write('hello world')
</script>

Output:

I love JS

hello world
(note how it didn’t wipe out the entire html screen)

What has to be done in order to wipe out everything on the page when using document.write()?

If used after the page has loaded (It's fully loaded before a user clicks a button. Everything is then wiped out after the button is clicked)

Show the code using document.write() that wipes out the entire page, leaving the replacement (hello world), upon the click of a button

alert() syntax for if you want Hello World to appear as an alert window upon the click of a button

(Note: window is optional. You can just use alert() instead of window.alert())

A way of displaying data in Javascript that is considered the developers best friend

console.log()

console.log() example syntax

Note: it's like an implicit/secret narration of what the user does. It's logged in your console

Syntax for printing a page upon the click of a button

Referred to as step by step instructions for the computer to follow

JavaScript statements

They end each statement. Making it easier for the browser to understand where one instruction ends and the next begins

;

Why is spacing important in code?

It makes it readable

Groups of statements wrapped in curly brackets. They keep related statements together. Mostly used in functions

Code blocks

Ways to declare variables

var let const

In making variables, what do you call the values you provide in the script? The values that are fixed

Literals

Two of the many types of literals

Numbers Strings

Combination of values, variables, and operators that get evaluated

Expression

How do you make single line comments in JavaScript

How do you make multi line comments in Javascript

/* comment */

What do you call JavaScript names

Identifiers/variables

What do you call the casing in variables wherein the first word starts with a lowercase but the rest of the words start in uppercase?

Camel case

A way of declaring a variable for values that don't change

const

When do you use let and how often should you use const?

Let is used when you're calculating. Const is always used

Confines variables inside blocks

block scope

Variables declared this way dont respect the block scope

var

You can't redeclare a variable with let and a block scope

With this type of variable declaration, you can use a variable before it is declared?

var

With this type of variable declaration, you cannot use a variable before it is declared

let

When declaring a const variable, there must be a value already assigned: const x ❎ const x=5 ✅

M7 JavaScript Flashcards

(50 cards)