In JavaScript, variables go through a simple lifecycle consisting of three stages: Declaration, Initialization, and Usage. Understanding these stages helps you manage your variables effectively, ensuring your code runs smoothly. Let’s explore each step.
1. Declaration
When you declare a variable, you’re telling JavaScript to create a spot in memory for that variable. This is done using keywords like var, let, or const. For example:
Here, age is declared but not yet assigned a value.
2. Initialization
Initialization is when you assign a value to the variable for the first time. You can do this at the time of declaration or later. For example:
If you write let age = 25;, the declaration and initialization happen at the same time.
3. Usage
Once a variable is declared and initialized, you can use it in your code. For example:
At this stage, you are reading or updating the value of the variable.
Key Points
- Declaration: Reserve memory for a variable.
- Initialization: Assign a value to the variable.
- Usage: Use the variable’s value in your code.
Understanding this lifecycle can help you avoid common errors, like trying to use a variable that hasn’t been declared or initialized yet.