Keywords, statements, and comments
In JavaScript programming, keywords, statements, and comments play an important role in defining or structuring the JavaScript program source code in multiple orders and developing the program from construct to output. Where keywords, statements, and comments perform individual functions or tasks at different times in the JavaScript program source code.
So, let’s get to know more about keywords, statements, and comments in JavaScript programs.
JavaScript Keywords – Keywords in JavaScript programming language are reserved words for specific programming tasks, which have a specific meaning or purpose in the particular JavaScript programming language. These keywords are used in JavaScript programs to perform some specific particular programming operations. JavaScript programmers cannot apply them as variable or function names. Because, unlike other programming languages, keywords in JavaScript are reserved for specific programming conditions or advancement capabilities.
Basic examples of reserved keywords in JavaScript programming.
- let, const, var datatype – These are used to declare multiple types of different program data type variables in JavaScript programs.
- javascript function – Used to define user defined function in JavaScript programs.
- if, else statement – Used to define or explain conditional statement in JavaScript programs.
- return statement – Used to return program value in JavaScript function program.
- for, while loop – Used to loop JavaScript program looping condition in start to end cycle.
- try, catch, finally keyword – Used in program error management in JavaScript programs.
- break, continue – Used to control the control flow of program loop in break or continue order in JavaScript programs.
- class, extends, super – Used to control or manage classes and inheritance properties in JavaScript programming.
JavaScript Reserved Keywords Variable Declaration Example.
let programming = “Javascript”; // here `let` is a keyword which is used for prgramming variable declaration
const contact = 9414; // here `const` is a keyword used for contact variable declaration
JavaScript program statement.
A statement in JavaScript programming is a reserved program instruction control flow in JavaScript programs, which tells the existing computer to perform a particular programming action or task immediately. Statements in JavaScript programs are usually executed line by line according to the given logic statement condition one after the other.
Popular statements in JavaScript programming are.
- Variable declarations – In JavaScript programs, variables are declared and assigned values.
- Assignment statements – In JavaScript programs, variables are assigned values.
- Conditional statements – In JavaScript program, which code is to be executed in conditional source based on the condition given by the particular programmer. It is decided in this.
- Looping statements – In JavaScript program, a statement logic or a block of code is executed again and again in start to end loop cycle order by the particular programmer.
Examples of statements in JavaScript programming.
Variable declaration statement in JavaScript.
let stu_name = “Siddhi”; // here srting variable Declaration and assignment value in one statement
const age=24;
if (age >= 21) {
console.log(“You are allowed to learn javascript.”);
} else {
console.log(“You are not allowed to learn javascript.”);
}
Javascript Looping Statement.
for (let p = 0; p < 10; p++) {
console.log(p); // result is – 0 to 9
}
Comments in JavaScript.
Comments in JavaScript programming are used to fulfill the documentation purpose of complex programming logic or condition. Remember, single line or multi line comments written in JavaScript program are ignored by the interceptor during program execution. Generally, there are two types of comments display methods in JavaScript program.
- Single-line comments – These comments start with // in JavaScript program, and are previewed till the end of the written comment row.
- Multi-line comments – These comments are displayed between /* and */ in JavaScript program, where multi-line comments can be more than one string in paragraph order.
Example of comments in JavaScript program.
JavaScript single-line comment.
// This is a single-line comment in JavaScript
let price = 999 ; // This is an inline or single line comment example
JavaScript multi-line comment.
/*
Here you can display multi-line text information.
This can be on more than one line in a JavaScript program.
*/
let course = “Javascript”;
Why and how to use comments in JavaScript programs?
- Explain code – Comments in any JavaScript program help new and old JavaScript developers to explain complex program logic conditions, what the source code is doing in the current program, it makes it easier for you and other developers to understand the source code later.
- Temporarily disable code comments – You can temporarily disable comments in any JavaScript program by commenting the program source code while debugging or testing the program.
- Provide context – Comments in JavaScript programs explain the reference or program logic in a simple text format, where you can know why a certain overview or logic condition was used in a particular program condition.
Example of combining keywords, statements, and comments in a // Declare variables
let programming = “Javascript”; // here programming variable define assign with javascript value
const price = 999; // here price is constant variable assign with 999 numeric value
/*
here if statement check if price more
899 then it print You are allowed
to learn javascript */
if (price > 998 ) { // here If price is 999 or greater
console.log(“\n You are allowed to learn javascript.”);
} else {
console.log(“\n You are not allowed to learn javascript.”);
}
Summary of Keywords, statements, and comments in JavaScript.
Remember that keywords are built-in specific purpose reserved words in JavaScript programming, such as, let, function, if, etc.
Statements are individual instruction commands or actions executed by a JavaScript program, such as, program variable value assignment, program loop, conditional statements, etc.
Comments in JavaScript programs are used to explain or annotate the program source code. These are ignored by the JavaScript engine during program execution, and do not affect the execution of any program source code written.
