JavaScript (JS) is a programming language that is used to create interactive and dynamic web pages. It is a client-side scripting language that is executed by web browsers. JS syntax is the set of rules that govern how JS code is written and structured. Understanding JS syntax is essential for writing efficient and effective code.
JS syntax is similar to other programming languages such as Java and C++. It consists of a set of rules that define how code should be written and structured. The syntax includes keywords, variables, operators, functions, and statements.
Keywords are reserved words that have a specific meaning in JS. They cannot be used as variable names or function names. Examples of keywords include var
, if
, else
, for
, and while
.
Variables are used to store data values. They are declared using the var
keyword followed by the variable name. Variables can hold different types of data such as numbers, strings, and boolean values.
Operators are used to perform operations on variables and values. Examples of operators include arithmetic operators such as +
, -
, *
, and /
, comparison operators such as ==
, !=
, <
, and >
, and logical operators such as &&
and ||
.
Functions are blocks of code that perform a specific task. They are declared using the function
keyword followed by the function name and parameters. Functions can be called multiple times and can return a value.
Statements are used to control the flow of the program. Examples of statements include if
statements, for
loops, and while
loops. Statements are executed in the order in which they appear in the code.
Here are some examples of JS syntax:
<script>
// declaring a variable
var x = 5;
// performing arithmetic operations
var y = x + 3;
var z = x * y;
// using if statement
if (z > 20) {
document.write("z is greater than 20");
} else {
document.write("z is less than or equal to 20");
}
// declaring a function
function greet(name) {
document.write("Hello, " + name + "!");
}
// calling a function
greet("John");
</script>
In this example, we declare a variable x
and assign it the value of 5. We then perform arithmetic operations on x
to get the values of y
and z
. We use an if
statement to check if z
is greater than 20 and display a message accordingly. We also declare a function greet
that takes a parameter name
and displays a greeting message. We call the greet
function and pass it the value "John".
JS syntax is the set of rules that govern how JS code is written and structured. Understanding JS syntax is essential for writing efficient and effective code. By following the rules of JS syntax, you can create interactive and dynamic web pages that provide a great user experience.