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Decorators are a feature of TypeScript that allow you to modify the behavior of a class, property, method, or parameter. They are a way to add additional functionality to existing code, and they can be used for a wide range of tasks, including logging, performance optimization, and validation.

Here’s an example of how you might use a decorator in TypeScript:

function log(
  target: Object,
  propertyKey: string | symbol,
  descriptor: PropertyDescriptor
) {
  const originalMethod = descriptor.value;

  descriptor.value = function (...args: any[]) {
    console.log(`Calling ${propertyKey} with arguments: ${args}`);
    return originalMethod.apply(this, args);

  return descriptor;

class Calculator {
  add(a: number, b: number): number {
    return a + b;

const calculator = new Calculator();
calculator.add(1, 2);
// Output: Calling add with arguments: 1,2
// Output: 3

In this example, we use the @log decorator to modify the behavior of the add method in the Calculator class. The log decorator logs the arguments passed to the method before calling the original method. This allows us to see what arguments are being passed to the method, without having to modify the method’s code.

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