Learn JavaScript Syntax

Part 1

Javascript syntax is based on Java syntax.

It is a set of rules.

This tutorial cover the syntax basics that will allow you to code with javascript (the text in grey is a comment)

Code Example:

                # declare variables
                var a, b, c,
# assign values
a = 4 ; b = 6;

# c = 10
c = b + a;

Part 2

JavaScript Literals


You can type numbers with decimals or without.

Code Example:

Try yourself >>


You can type strings with double or single quotes.

Code Example:

Try yourself >>

Part 3

JavaScript Values

There are two types of values:

variable values and Fixed values

Variable values are called variables.

Fixed values are called literals.

Part 4

JavaScript Operators

to compute values, Javascript uses operators such: ( / * + - )

Visit our Javascript Arithmetic Opeartors reference to learn the full guide of Javascript Arithmetic operators

Code Example:

( 40 - 10 ) * 2

Try yourself >>

to assign values, Javascript uses assignment operators: ( = )

Visit our Javascript Assignment Opeartors reference to learn the full guide of Javascript Assignment operators

Code Example:

var y, x,
y = 4 ;
x = 2 ;

Try yourself >>

Part 5

JavaScript Expressions

When we combine variables, values, and operators, it is called evaluation

For example, 2 * 5 evaluates to 10:

Code Example:

2 * 5

Try yourself >>

Expressions can also contain variable values:

Code Example:

z * 2

Try yourself >>

tip: You can also use numbers or strings, so "Bruce" + "Clynt" evaluates "Bruce Clynt"

Part 6

JavaScript Variables

Variable is used to store data value.

Use the var keyword to declare variable.

You can also use = sign to assign values to variables.

Next example shows how Z is defined as var (variable), then we give Z which is now variable the value of 10

Code Example:

var z;
z = 10;

Try yourself >>

Visit our Javascript Variables reference to learn the full guide of Javascript Variables

Part 7

JavaScript Comments

Some Javascript statements are not "Executed"

Any of these three /* // */ signs are used to write comment that the computer will not execute and ignore.

Code Example:

var z = 10 ; // This will be executed
// var x = 11; this will NOT be executed

Try yourself >>

Visit our Javascript Comments reference to learn the full guide of Javascript Comments

Part 8

JavaScript Keywords

Keywords order the browser to create variables, the var in the example below is keyword:

Code Example:

var z, x;
x = 2 + 3 ;
z = x * 2 ;

Try yourself >>

We can't use some of the keywords, Visit our Javascript Reserved words reference to learn the full guide of Javascript Reserved words

Part 9

JavaScript Identifiers

Identifier is used to name variables, keywords, labels, and functions.

The first character must be a letter, or an underscore or a dollar sign

tip: You can't type numbers as first character of identifier.

tip: Identifiers are case sensitive, David and david, are not the same variables.

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