- You should follow these rules to maintain your code neat and bug-free.
Syntax and Case Sensitivity
var a = 7; var b = 5; var c = a + b;
To begin with, the first character of an identifier has to be either a letter, a dollar sign (
$), or an underscore (
_). So, for example,
Note: a number cannot be the first character of an identifier.
Name = "Joe"; name = "John"; // Now we have two separate string variables
Note: same rules apply to keywords and other identifiers as well.
Whenever case sensitivity is relevant, it's important to have a clear standard of writing names that consist of more than one word. Throughout the history of programming, there have been three most popular methods to achieve that: hyphens (
first-name), underscores (
first_name), and camel case (
Types of Literals
Note: Be sure to use a decimal point (
.) and not a comma (
Another type of a literal is a string. It defines a piece of text within quotes. String values can be written in single or double quotes:
var name1 = "value1"; var name2 = 'value2';
Note: A string does not necessarily have to have a written value and can be an empty string instead.
Boolean literals have two values: either
false. Check out the example below:
var xyz = true; var xyz = false;
Theory is great, but we recommend digging deeper!
Variables and Operators
var keyword when declaring variables. You can assign values to variables using an equal sign
In the example below, we declare a new variable
a and assign a value to it:
var a; a = 10;
You should use the assignment operator (
var a = 20;
When you need to define calculations, you can also use other arithmetic operators (
/) for computing values. These operators must also be separated with spaces, as it makes the code easy to read:
(7 + 5) * 12
2 * 2 will evaluate to
4, like in the example below:
var a = 2 * 2;
Some expressions can include variables as well. However, this is not mandatory - you don't have to include them if you don't need them.
a * 8
The values can also be both variables and strings combined. For example, the expression
"Joe" + " " + "Johnson", will evaluate to
"Joe" + " " + "Johnson"
Keywords and Comments
var tells the browser to create a new variable:
var a = 7 + 5; var b = a * 12;
// or in between
*/ is referred to as a comment. This function is similar to HTML Comments.
Comments are ignored by the browser and not displayed:
var a = 7; // This statement is going to be executed // var b = 5; This statement is not going to be executed. It is just a comment