Hoodie exercise

how much detail you need to tell it to do something

JavaScript

a script is like a resipes/handbook/manual - series of instructions that a computer follows to achieve a goal.

each time the script runs it might only use a subset of all the instructions

computers approach tasks in a different way than humans, so your instructions must let the computer solve the tasks programmatically

1. define the goal
2. design the script
3. code each step

Expressions and Operators

an expression results in a single value - 2 types

• expressions that assign a value to a variable

• expressions that use 2 or > values to return a single value

• assignment operators color = ‘white’
• arithmetic operators area = 40 + 1
• string operators ‘Hi’ + ‘Master Fizzo’
• comparison operators buy = 3 > 5 {false}
• logical operators buy = (5 > 3) && (2 < 4) {true}

variables are used to temporarily store data stored in the script arrays are special types of variables that store more than 1 piece of info JS - numbers(0-9) , strings(text) , Boolean (t/f)

functions - group a series of statements 2 perform specific task use function 2 repeat part of script - no re write code

example insert new text into an html - by grabbing onto an ID

declaring a function:

function sayHello() { document.write('Hello you'); }

calling a function

sayHello();

declaring functions that need more info

function getArea(width,height) { return width * height; }

calling functions that need info

getArea(3,5); or width = 3; height = 5; getArea(width, height);

getting a single value out of a function

function calcArea(width, height) { ` var area = width * height; return area; makes the script stop and return to where it was } var wall_1 = calcArea(3, 5); var wall_2 = calcArea(8, 5);`

getting multiple values out of a function

function getSize(width, height, depth) { ` var area = width * height; var volume = width * height * depth; var sizes = [area, volume]; return sizes; } var area51 = getSize(3,2,4)[0]; var volume51 = getSize(3,2,4)[1];`

function declaration and function expression

function area(width, height) { ` return width * height; } var size = area(3, 4);`

compared to

var area = function(width, height) { ` return width * height; }; var size = area(3, 4);`

first one (function declaration) can be called before script runs over it where as the second one (function expression) cannot