What is the difference between parameters and arguments in TypeScript?

In TypeScript, parameters and arguments are two fundamental concepts that play distinct roles during function invocation.

Parameters

Parameters are the variable names specified when defining a function, representing the data that the function can accept. They specify the types of data the function can accept and the names of these parameters. In TypeScript, you can also define types for these parameters, which enhances code readability and reduces errors.

Example:

typescript
function greet(name: string, age: number): string {
    return `Hello, ${name}! You are ${age} years old.`;
}

In the above example, name and age are the parameters of the greet function, and string and number are the types of these parameters respectively.

Arguments

Arguments are the specific values provided when calling a function. These values are passed to the function, which then uses them to execute its operations. The number and types of arguments must match those specified in the function definition.

Example:

typescript
const message = greet('Alice', 30);
console.log(message); // Output: Hello, Alice! You are 30 years old.

In this call, 'Alice' and 30 are the arguments passed to the greet function. These arguments correspond to the name and age parameters defined in the function.

Summary

Overall, parameters are part of the function definition, specifying the data that the function accepts and the types of these data. Arguments are the specific values provided during function invocation, which are used in place of the parameters defined in the function for execution.

Properly using parameters and arguments in TypeScript can make the code more robust, reduce errors, and increase clarity and maintainability.