Read: 06 - Programming with JavaScript

What is JavaScript ?

JavaScript allows you to make web pages more interactiv by accessing and modifying the content and marckup used in a web page while it is begin viewed in the browser

How js makes web pages more interactive

• Access contact You can use JavaScript to select any element, attribute, or text from an HTML page
• Modify content You can use JavaScript to add elements, attributes, and text to the page, or remove them.
• Program rules You can specify a set of steps for the browser to follow (like a recipe), which allows it to access or change the content of a page.
• React to event You can specify that a script should run when a specific event has occurred.

JavaScript includes following categories of operators.

• Arithmetic Operators
• Comparison Operators
• Logical Operator
• Assignment Operators
• Conditional Operators)

EXPRESSIONS

An expression evaluates into (results in) a single value. Broadly speaking there are two types of expressions.

• EXPRESSIONS THAT JUST ASSIGN A VALUE TO A VARIABLE : var color = ‘beige’;
• EXPRESSIONS THAT USE TWO OR MORE VALUES TO RETURN A SINGLE VALUE var area = 3 * 2;

OPERATORS

Functions

Functions are one of the fundamental building blocks in JavaScript. A function in JavaScript is similar to a procedure—a set of statements that performs a task or calculates a value, but for a procedure to qualify as a function, it should take some input and return an output where there is some obvious relationship between the input and the output. To use a function, you must define it somewhere in the scope from which you wish to call it.