What is Variable Shadowing in JavaScript and How Can It Affect Code Execution?

Variable Shadowing in JavaScript

Understanding variable shadowing is a crucial concept in JavaScript programming. It refers to the ability of a variable declared within a function to have the same name as a variable declared in a wider scope. This can lead to unexpected behavior in your code.

Let's explore a simple example to illustrate variable shadowing:

<code class="js">var currencySymbol = "$";

function showMoney(amount) {
  var currencySymbol = "€";
  console.log(currencySymbol + amount);
}

showMoney("100");</code>

In this code, we define a global variable named currencySymbol with a value of "$". Inside the showMoney function, we declare another variable named currencySymbol and assign it a value of "€".

When the showMoney function is called, the inner currencySymbol variable overrides the global currencySymbol variable. As a result, the JavaScript interpreter prints the Euro symbol ("€"), not the dollar symbol ("$").

This is known as variable shadowing. The inner variable "shadows" the outer variable, making it inaccessible within the function.

In conclusion, variable shadowing in JavaScript occurs when a variable declared within a function shares the same name as a variable declared in a wider scope. The inner variable takes precedence, leading to the outer variable effectively being inaccessible from within the function. Understanding variable shadowing is essential for writing effective and maintainable JavaScript code.

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