JavaScript Default Parameters

JavaScript default parameters allow you to set default values for function parameters. This feature simplifies function calls and provides default behavior when no argument is provided.

Key Concepts

• Default Values: You can specify default values for parameters in function declarations.
• Function Invocation: If an argument is not passed during a function call, the default value is used.

Syntax

To set a default parameter, you can use the following syntax:

function functionName(parameter1 = defaultValue1, parameter2 = defaultValue2) {
    // Function body
}

Example

Here's a simple example to illustrate default parameters:

function greet(name = "Guest") {
    console.log("Hello, " + name);
}

greet("Alice"); // Output: Hello, Alice
greet();        // Output: Hello, Guest

Explanation of the Example

• In the greet function, the parameter name has a default value of "Guest".
• When calling greet("Alice"), the output is "Hello, Alice" because the argument "Alice" is provided.
• When calling greet() without an argument, the output is "Hello, Guest" because the default value is used.

Benefits of Default Parameters

• Improves Readability: Functions are easier to read and understand.
• Reduces Errors: Helps avoid errors related to undefined values.
• Simplifies Code: Eliminates the need for manual checks for undefined values.

Conclusion

JavaScript default parameters are a powerful feature that enhances the flexibility and usability of functions. By providing default values, developers can create more robust and user-friendly code.