Read: 04a - Dynamic web pages with JavaScript
HOW HTML, CSS,& JAVASCRIPT FIT TOGETHER?
you need to know how it will fit together with the HTML and CSS in your web pages befor Before diving into the JavaScript language.
The developer must have knowledge of HTML , CSS AND JS the languages that are linked by a link that has a link between them

HOW A BROWSER SEES A WEB PAGE
You have to know how js works to know how it works , All major browsers use a JavaScript interpreter to translate your instructions into instructions the computer
- RECEIVE A PAGE AS HTML CODE
- CREATE A MODEL OF THE PAGE AND STORE IT IN MEMORY
- USE A RENDERING ENGINE TO SHOW THE PAGE ON SCREEN
HOW HTML, CSS & JAVASCRIPT FIT TOGETHER
you need to know how it will fit together with the HTML and CSS in your web pages , befor learning JavaScript language
- CONTENT LAYER
- html files This is where the content of the page lives. The HTML gives the page structure and adds semantics.
- PRESENTATION LAYER
- css files The CSS enhances the HTML page with rules that state how the HTML content is presented (backgrounds, borders, box dimensions, colors, fonts, etc.).
- BEHAVIOR LAYER
- js files This is where we can change how the page behaves, adding interact ivity. We will aim to keep as much of our JavaScript as possible in separate files.
Basic javascript instructions
-
A script is made up of a series of statements. Each statement is like a step in a recipe.
-
Scripts contain very precise instructions. For example, you might specify that a value must be remembered before creating a calculation using that value.
-
Variables are used to temporarily store pieces of information used in the script.
you can writt vaariables in javaScript like Creating a variable in JavaScript is called “declaring” a variable: var carName
After the declaration, the variable is empty (it has no value)
To assign a value to the variable, use the equal sign: carName = “Volvo”
Syntax var varname = value;
javascript variable
look to the picers

DATA TYPES
- Numeric Data 57
- String Data ‘hi ,miss u’
- Boolean Data true
example

to read more click here link