if else in JavaScript - Conditional Statements
Tags: javascript, webdev, programming, tutorial
Published: 2022-02-18 04:58:18

Bill Gates's once said, "Computer programming is calculation of math and making decision with if..else".

And it is hard to argue with that statement, and why not. Because deep down this is what programming all about.

If you are new to this programming world, consider going through this article for a better reference.: 
📌[3 Things to learn while Programming](https://withinbracket.com/posts/3-things-to-learn-while-programming/) 

Anyway, if you been in computer programming for a while, you probably know that programs are build upon `logics`. 
And a logic need to go though certain condition to satisfy a particular problem.

This is where `conditional statements` comes into the picture. They help us to make decisions to ace a problem.

Generally the `conditional statements` are referred as `if...else`. And they are pretty straight forward: 

```js
if(this happen){
  do this particular task;
}else{
  do this.
}
```
Which means, if `certain` condition met, do a **particular** task, and if the condition is not met, then
do **something** else.

```js
let num = 1;
if(num > 0){ 
   console.log("The number is poditive");
} else {
   console.log("The number is negative");
}
```

## Types of Conditional Statement

Typically there are two types of conditional statement exists, in any programming language:
- if...else
- else if

Let's check out them individually:

## if...else 

Syntax:

```js
if(this condition satisfies){
   do a particular task
} else {
   do something else.
}
```

This syntax is similar to what we discuss earlier. If a condition `satisfies`, do a **particular** task,
otherwise do something else.

Example:

```js
// Check if a number is odd or even
let num = 7;
if(num % 2 == 0){
   console.log("The number is even");
} else {
   console.log("the number is odd");
}
```

In the above example, we have checked that while dividing a number by 2, if we get `0` as **reminder** then 
the number is `even`, and if we get `1` as reminder then the number is `odd`.

Note: '%' is the **modulo operator** which gives the `reminder` while divide a number, 
whereas '/' gives the `quotient `.{#quote .info__quote}

## else if

Apart from `if...else`, we have `else if`, which is use to add another **condition**.

Syntax:

```js
if(this condition satisfies){
   do a particular task
} else if(check this condition){
   do this task
} else {
   do something else.
}
```
In this syntax, you can easily see that here is an another `condition` to be check.

We can add as many conditions as we want to be checked, with the help of `else if`.

Example:

```js
let num = 5;
if(num > 0){
   console.log("The number is positive");
} else if(num == 0){
   console.log("The number is ZERO");
} else {
   console.log("The number is negetive");
}
```

Quite obvious; In the above program we also check that whether or not is the number is `0`, 
and print `log` statement associated with that `condition`, using `else..if`.

## The Nested Condition

So far now, we have checked out, what is a conditional statement and its type. But we have a another version 
of conditional statement with **nesting**.

Nesting means checking a condition **inside** a particlular condition.

❕ Make Sence ? Check this example:

```js
let num1 = 5;
let num2 = 8;
if(num1 == num2){
   console.log("Both number are equal");
} else {
   if(num1 > num2){
      console.log("num1 is greater than num2");
    } else {
      console.log("num1 is lesser than num2");
    }
}
```

In the above example we have a `if..else` statement. But inside the `else` block we have
another `if..else` statement. This is called Nested Conditional Statement.

## Things to Remember:

So here we have learned about the conditional statement, but there are some facts you should
consider while using them.

- `else` always should be followed by a `if` statement
- use `else if` only if you need to check for another condition
- If `else` done your job, `else if` might not require to add

## Conclusion;

So let's wrap this up. In any programming language we have two kind of conditional statement:
- if..else
- else if

We also have a nested conditional statement, to check a condition inside a condition.

And this is all about conditional statement in JavaScript.