---
title: "When do I use var in coding?"  
description: "When do I use var in coding?"  
author: "Utpal Vishwas"  
published: 2023-07-07  
updated: 2023-07-10  
canonical: https://www.mindstick.com/forum/159004/when-do-i-use-var-in-coding  
category: "coding principles"  
tags: ["programming language", "coding standard", "coding"]  
reading_time: 2 minutes  

---

# When do I use var in coding?

When do I use [var](https://www.mindstick.com/forum/33920/what-is-different-var-and-dynamic-types-in-c-sharp) in [coding](https://www.mindstick.com/articles/12290/teaching-coding-from-the-metal-up-or-from-the-glass-back)?

## Replies

### Reply by Aryan Kumar

The `var` keyword is used to declare variables in JavaScript. It is the oldest and most widely supported way to declare variables in JavaScript. However, it is not recommended for use in modern JavaScript code.

There are two main reasons why `var` is not recommended:

- **Hoisting:** `var` declarations are hoisted to the top of their scope, which can lead to unexpected behavior. For example, the following code will assign the value `5` to the variable `x`, even though the `var x` declaration is not until the end of the function:

Code snippet

```plaintext
function myFunc() {
  console.log(x); // 5
  var x = 5;
}
```

- **Block scoping:** `var` variables are scoped to the function in which they are declared, not to the block in which they are declared. This can lead to confusion and errors, especially when working with nested blocks. For example, the following code will assign the value `10` to the variable `x`, even though the `var x = 5` declaration is inside the inner block:

Code snippet

```plaintext
function myFunc() {
  if (true) {
    var x = 10;
  }
  console.log(x); // 10
}
```

If you are writing modern JavaScript code, you should use the `let` or `const` keywords to declare variables. These keywords are newer and offer more features than `var`, such as block scoping and no hoisting.

Here is a table summarizing the differences between `var`, `let`, and `const`:

| Keyword | Scope | Hoisting |
| --- | --- | --- |
| `var` | Function | Yes |
| `let` | Block | No |
| `const` | Block | No |

In general, you should use `let` for variables that you need to reassign, and `const` for variables that you never need to reassign.

Here are some examples of when you might use `var`:

- If you are writing code that is not compatible with modern JavaScript browsers.
- If you are writing code that needs to be compatible with older versions of JavaScript.
- If you are writing code that needs to be compatible with other programming languages that use the `var` keyword.

However, if you are writing modern JavaScript code, you should avoid using `var` and use `let` or `const` instead.


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Original Source: https://www.mindstick.com/forum/159004/when-do-i-use-var-in-coding

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