Difference between var and let in JavaScript example practice. #javascript #js #coding #programming

In JavaScript, `let` and `var` are both used to declare variables, but they have some important differences:

1. **Scope**:
- `var` is function-scoped, meaning it is accessible throughout the function in which it is declared.
- `let` is block-scoped, meaning it is only accessible within the block (e.g., within `{}`) where it is declared.

2. **Hoisting**:
- Variables declared with `var` are hoisted to the top of their scope and initialized with `undefined`, so they can be referenced before they are declared.
- Variables declared with `let` are also hoisted, but they are not initialized. This means referencing them before their declaration results in a `ReferenceError`.

3. **Re-declaration**:
- `var` allows re-declaration of the same variable within the same scope without any issues.
- `let` does not allow re-declaration within the same scope, which helps prevent accidental overwriting of variables.

Here's a quick example to illustrate these differences:

```javascript
// Using var
var x = 5;

// Using let
let y = 5;
```

Would you like to know more about how `const` compares to `let` and `var`?

Source: Conversation with Copilot, 9/6/2024