Lesson 4
Variable Initialization
Learn how to assign a value to a variable at the time of declaration or later.
Initialization is the process of assigning an initial value to a variable.
A variable can be initialized at the time of declaration or later in the program.
At Declaration
let name = "Vivek";const PI = 3.14;After Declaration
let count;count = 10;Before Initialization
let score;Memory
undefined
After Initialization
let score = 100;Memory
100
Bad Example
let age;console.log(age);Output: undefined (Not recommended)
Good Example
let age = 25;console.log(age);Output: 25 (Recommended)
- Forgetting to initialize variables.
- Using variables before initialization.
- Assuming uninitialized variables have a value.
- Confusing declaration with initialization.
Initialize the variables as shown below.
JavaScript
- Initialization assigns a value to a variable.
- You can initialize at declaration or later.
- Uninitialized variables have undefined.
- Good initialization leads to predictable code.