JavaScript Hoisting
Tags: javascript, makstyle119, beginners, hoisting
Published: 2023-03-24 14:38:40

**[JavaScript](https://www.javascript.com/)** is a popular programming language used by developers to build **interactive** and **dynamic** web applications. One of the **unique** features of **[JavaScript](https://www.javascript.com/)** is **hoisting**. In this blog post, we'll explore what **hoisting** is and how it works in **[JavaScript](https://www.javascript.com/)**.

What is **hoisting** in **[JavaScript](https://www.javascript.com/)**?

**Hoisting** is a term used to describe the **behavior** of **[JavaScript](https://www.javascript.com/)'s** **variable** and **function** **declarations**. It is the **process** of moving **variable** and **function** **declarations** to the top of their respective **[scopes](https://dev.to/makstyle119/scope-in-javascript-4b9n)**. This means that even if a **variable** or **function** is **declared** after it is used, **[JavaScript](https://www.javascript.com/)** will move the **declaration** to the top of the **scope** and allow the **code** to **execute** without **error**.

**Hoisting** is an important concept to understand because it can affect the **behavior** of your **code**. If you don't understand how **hoisting** works, it can lead to **bugs** and **unexpected** results in your **code**.

**Variable Hoisting:**

**Variable hoisting** is the process of moving variable **declarations** to the top of their **respective scopes**. However, it's **important** to note that only the **declaration** is **hoisted**, not the **assignment**.

For **example**, consider the following **code**:

{% embed https://gist.github.com/makstyle119/9c334b90d59a64658611ce1cf1c53278.js %}

In this **code**, we **declare** a **variable** called ``myVariable`` and then **immediately** try to **log** its **value** to the **console**. However, because the **declaration** is **hoisted** to the top of the **scope**, the ``console.log`` statement does not **throw** an **error**. Instead, it **logs** ``undefined``.

This is **because** when the **code** is **executed**, **[JavaScript](https://www.javascript.com/)** first **hoists** the **variable declaration** to the top of the **scope**. This means that the **variable** ``myVariable`` is **declared** with a **value** of ``undefined``. Then, when the ``console.log`` **statement **is **executed**, the **variable** has not yet been assigned a **value**, so it **logs** ``undefined`` to the **console**.

**Function Hoisting:**

**Function hoisting** is **similar** to **variable hoisting**, but it **applies** to **function declarations** instead of **variable declarations**. When a **function** is **declared** using the ``function`` **keyword**, its **entire declaration** is **hoisted** to the top of the **scope**.

For **example**, consider the following **code:**

{% embed https://gist.github.com/makstyle119/88ced8d1917d672d66511484d774ab54.js %}

In this **code**, we **declare** a **function** called ``myFunction`` and then immediately call it. However, because the **function declaration** is **hoisted** to the top of the **scope**, the **code** executes without **error** and **logs** "Hello World!" to the **console**.

This is because when the **code** is **executed**, **[JavaScript](https://www.javascript.com/)** first **hoists** the **function declaration** to the top of the **scope**. Then, when the **function** is called, it has already been **declared** and can be **executed** without **error**.

**Conclusion:**

**Hoisting** is a **unique** feature of **[JavaScript](https://www.javascript.com/)** that can be helpful in some cases, but can also lead to **bugs** and **unexpected behavior** if not used properly. By **understanding** how **[variable](https://dev.to/makstyle119/variables-in-javascript-206o)** and **function hoisting** works, **developers** can write more **efficient** and **error-free code**. However, it's important to use **hoisting** with care and consideration, and to be aware of its **potential pitfalls**.