JavaScript syntax refers to the rules and conventions dictating how code is structured and arranged within the JavaScript programming language. This includes statements, expressions, variables, functions, operators, and control flow constructs.
Syntax
console.log("Basic Print method in JavaScript");JavaScript syntax refers to the set of rules that determines how JavaScript programs are constructed:
// Variable declaration
let c, d, e;
// Assign value to the variable
c = 5;
// Computer value of variables
d = c;
e = c / d;
JavaScript Values
There are two types of values defined in JavaScript Syntax:
- Fixed Values: These are known as the literals.
- Variable values: These are called variables
These are the features of JavaScript which have some predefined syntax:
JavaScript Literals
Syntax Rules for the JavaScript fixed values are:
- JavaScript Numbers can be written with or without decimals.
- Javascript Strings are text that can be written in single or double quotes.
JavaScript
let num1 = 50
let num2 = 50.05
let str1 = "Geek"
let str2 = 'Geeks'
console.log(num1)
console.log(num2)
console.log(str1)
console.log(str2)
Output50
50.05
Geek
Geeks
JavaScript Variables
A JavaScript variable is the simple name of the storage location where data is stored. There are two types of variables in JavaScript which are listed below:
Example: This example shows the use of JavaScript variables.
JavaScript
// Declare a variable and initialize it
// Global variable declaration
let Name = "Apple";
// Function definition
function MyFunction() {
// Local variable declaration
let num = 45;
// Display the value of Global variable
console.log(Name);
// Display the value of local variable
console.log(num);
}
// Function call
MyFunction();
Output:
Apple
45
JavaScript Operators
JavaScript operators are symbols that are used to compute the value or in other words, we can perform operations on operands. Arithmetic operators ( +, -, *, / ) are used to compute the value, and Assignment operators ( =, +=, %= ) are used to assign the values to variables.
Example: This example shows the use of javascript operators.
JavaScript
// Variable Declarations
let x, y, sum;
// Assign value to the variables
x = 3;
y = 23;
// Use arithmetic operator to
// add two numbers
sum = x + y;
console.log(sum);
JavaScript Expressions
Javascript Expression is the combination of values, operators, and variables. It is used to compute the values.
Example: This example shows a JavaScript expression.
JavaScript
// Variable Declarations
let x, num, sum;
// Assign value to the variables
x = 20;
y = 30
// Expression to divide a number
num = x / 2;
// Expression to add two numbers
sum = x + y;
console.log(num + "\n" + sum);
JavaScript Keywords
The keywords are the reserved words that have special meanings in JavaScript.
// let is the keyword used to
// define the variable
let a, b;
// function is the keyword which tells
// the browser to create a function
function GFG(){};The comments are ignored by the JavaScript compiler. It increases the readability of code. It adds suggestions, Information, and warning of code. Anything written after double slashes // (single-line comment) or between /* and */ (multi-line comment) is treated as a comment and ignored by the JavaScript compiler.
Example: This example shows the use of javascript comments.
JavaScript
// Variable Declarations
let x, num, sum;
// Assign value to the variables
x = 20;
y = 30
/* Expression to add two numbers */
sum = x + y;
console.log(sum);
JavaScript Data Types
JavaScript provides different datatypes to hold different values on variables. JavaScript is a dynamic programming language, which means do not need to specify the type of variable. There are two types of data types in JavaScript.
- Primitive data type
- Non-primitive (reference) data type
// It store string data type
let txt = "GeeksforGeeks";
// It store integer data type
let a = 5;
let b = 5;
// It store Boolean data type
(a == b )
// To check Strictly (i.e. Whether the datatypes
// of both variables are same) === is used
(a === b)---> returns true to the console
// It store array data type
let places= ["GFG", "Computer", "Hello"];
// It store object data (objects are
// represented in the below way mainly)
let Student = {
firstName: "Johnny",
lastName: "Diaz",
age: 35,
mark: "blueEYE"
}JavaScript Functions
JavaScript functions are the blocks of code used to perform some particular operations. JavaScript function is executed when something calls it. It calls many times so the function is reusable.
Syntax:
function functionName( par1, par2, ....., parn ) {
// Function code
} The JavaScript function can contain zero or more arguments.
Example: This example shows the use of Javascript functions.
JavaScript
// Function definition
function func() {
// Declare a variable
let num = 45;
// Display the result
console.log(num);
}
// Function call
func();
JavaScript Identifiers
JavaScript Identifiers are names used to name variables and keywords and functions.
A identifier must begin with:
- A letter(A-Z or a-z)
- A dollar sign($)
- A underscore(_)
Note: Numbers are not allowed as a first character in JavaScript Identifiers.
JavaScript Case Sensitive
JavaScript Identifiers are case-sensitive.
Example: Both the variables firstName and firstname are different from each other.
JavaScript
let firstName = "Geek";
let firstname = 100;
console.log(firstName);
console.log(firstname);
JavaScript Camel Case
In JavaScript Camel case is preferred to name a identifier.
Example:
let firstName
let lastName
JavaScript Character Set
A unicode character set is used in JavaScript. A unicode covers the characters, punctuations and symbols.
We have a complete article on character sets. Click here to read Charsets article.
JavaScript Syntax – FAQs
What is the basic syntax of JavaScript?
The basic syntax of JavaScript includes statements, expressions, variables, functions, operators, and control flow constructs. A typical JavaScript statement ends with a semicolon and can include variable declarations, function calls, loops, and conditionals.
What is the syntax for defining a JavaScript function?
The syntax for defining a function in JavaScript is:
function functionName(parameter1, parameter2) {
// Code to be executed
}
This function can then be called using functionName(argument1, argument2);.
Is JavaScript syntax easy to learn?
Yes, JavaScript syntax is considered easy to learn, especially for beginners. It is intuitive and has a C-like structure, which is familiar to those who have experience with languages like C, C++, or Java.
What is the JavaScript syntax for embedding code in HTML?
JavaScript code is embedded in HTML using the <script> tag. The script can be placed within the <head> or <body> sections of the HTML document, or it can be included as an external file:
<script>
// JavaScript code here
</script>
What does “syntax” mean in coding?
In coding, “syntax” refers to the set of rules that defines the structure and format of the code in a programming language. It dictates how code should be written so that it can be correctly interpreted and executed by the compiler or interpreter.
