Expression vs. Statement

Aditya Chakraborty — Tue, 21 Jun 2022 11:15:26 +0000

We programmers are in a lot of confusion between Expression and Statement. The purpose of this article is to clear this subject through a short overview.

The basic difference between an expression and a statement is that the expression returns something at the end of the day, produces data, and can be stored in one place. And the statement does not produce any data, cannot be stored anywhere, does not return anything. Defining a function is statement, and function call is expression. Because when you write a function, it does not return anything until the function is called. If the arrow function is written, it is an expression because it is being stored in a variable. Let's look at some examples.

const name1 = 'Rayhan'; // Statement
const name2 = 'Alvi'; // Statement
const name3 = 'Anik'; // Statement
const name4 = 'Arjun'; // Statement
const name5 = 'Ayman'; // Statement

All of these are statements. Because they do not return anything.

const students = [
    'Rayhan',
    'Alvi',
    'Anik',
    'Arjun',
    'Ayman',
    'Ayuub',
    'Bidyut',
]; // Statement

console.log(students[0]); // Expression
console.log(students[1]); // Expression
console.log(students[2]); // Expression
console.log(students[3]); // Expression
console.log(students[4]); // Expression

for (let i = 0; i < students.length; i++) {
    console.log(students[i], students[i].toLowerCase()); // Expression
} // Statement

students is statement, because it is not returning anything. console.log() is expression, because it returns something. for loop is statement, because it does not return anything, but console.log(students[i], students[i].toLowerCase()) inside the for loop is expression.

function nameOfFunction(name) {
    if (!name) {
        console.log('Please provide your name');
    } else {
        console.log('Hello', name);
    }
} // Statement

This is called function statement. Because, it will not return anything until it is called.

const nameOfFunction = function (name) {
    if (!name) {
        console.log('Please provide your name');
    } else {
        console.log('Hello', name);
    }
} // Expression

This is called function expression, because it is stored in a variable.

nameOfFunction('Murshed'); // Expression
nameOfFunction('Fahim'); // Expression
nameOfFunction(); // Expression

Any function call is expression, because it returns something. If there is nothing to return it returns at least undefined.

function generateRandomNumber(min = 1, max) {
    const randomNumber = Math.floor(Math.random() * min + (max - min)); // Statement
    return randomNumber; // Expression
} // Statement

console.log(generateRandomNumber(5, 10)); // Expression

This is the last example. Defining the function generateRandomNumber is statement, const randomNumber = Math.floor(Math.random() * min + (max - min)) is statement, Math.floor(Math.random() * min + (max - min)) is expression, return randomNumber is expression, console.log(generateRandomNumber(5, 10)) is expression.

I tried to give a short overview to clear the concept of expression and statement. Hope you can understand. 😊😊

Importance of reading documentation

Aditya Chakraborty — Tue, 19 Apr 2022 07:58:18 +0000

Basically we, the beginners, are too bored to read the documentations. This is normal. Because, we don't have that much patience to read the large size of documentation. So, what do we do normally? We watch tutorials one to another. But, when we learn something from one tutorial and want to do some projects from another tutorials, we feel completely empty. Sometimes, we find that what is being shown in the current tutorial is not shown in the previous tutorial. We trapped in tutorial hell.

But when we learn something by reading documentation, we have all the topics of that programming language in front of us. We don't need to memorize everything. Just follow the documentation and practice accordingly. Then no matter from which you watch the tutorial, you don't feel everything is new. It is very important to develop this habit. Because it is impossible to teach 100% for anyone. That is why, everything is stated in the documentation. If you watch tutorial by not reading documentation, you will be trapped in tutorial hell. You can't learn anything. That is why, it is very important to read documentation. If you habituated to read documentation, learning process becomes too easy. You don't need to worry then, where I can find the best tutorial, who created the best content etc. You will learn anything by reading just docs. There are two awesome websites for learning programming languages. w3schools and MDN.

These two websites are the alphabet books of the programming languages. You can write big big essay, when you learn the alphabets properly. My personal recommendation for the beginners is w3schools.

So, my suggestion to all the beginners is please habituated to learn documentation. You don't regret.

Happy Learning.

DEV Community: Aditya Chakraborty

Expression vs. Statement

Importance of reading documentation