Introduction

TypeScript, a superset of JavaScript, continues to evolve, bringing new features that enhance developer productivity and code quality. In this blog, we will explore some of the latest features in TypeScript that every developer should know about.

NoInfer Utility Type

The NoInfer utility type allows developers to prevent TypeScript from inferring types for certain values. This feature is useful for maintaining strict type checks and ensuring that specific types are not inferred during function calls.

Example:

function process<T>(value: T, inferred: NoInfer<T>): T {
  return value;
}

Object.groupBy and Map.groupBy

These new static methods allow developers to group elements of an array into objects or maps based on a key function. This provides a cleaner and more efficient way to handle collections of data.

Example:

const array = [0, 1, 2, 3, 4, 5];
const groupedByObject = Object.groupBy(array, num => (num % 2 === 0 ? "even" : "odd"));
console.log(groupedByObject); // { even: [0, 2, 4], odd: [1, 3, 5] }

const groupedByMap = Map.groupBy(array, num => (num % 2 === 0 ? "even" : "odd"));
console.log(groupedByMap); // Map { 'even' => [ 0, 2, 4 ], 'odd' => [ 1, 3, 5 ] }

Module Resolution Enhancements

TypeScript introduces improvements in module resolution with the --moduleResolution bundler and --module preserve options. These settings make it easier to integrate with modern bundlers and handle various module formats more effectively.

Checked Import Attributes and Assertions

Import attributes and assertions are now checked against a global ImportAttributes type, allowing for more accurate and type-safe imports. This ensures that import statements are correctly validated and handled by the TypeScript compiler.

Quick Fix for Missing Parameters

TypeScript now provides a quick fix for functions called with too many arguments. This feature automatically suggests adding missing parameters, streamlining the development process and reducing errors.

Decorators

TypeScript's decorator support has been enhanced to align with the latest ECMAScript proposals. Decorators can now be used on methods, properties, and even entire classes, allowing for more modular and reusable code structures.

Example:

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

class Example {
  @log
  sayHello(name: string) {
    return `Hello, ${name}`;
  }
}

const example = new Example();
example.sayHello('World'); // Logs: Calling sayHello with ["World"]

Enums Improvements

TypeScript introduces hybrid enums, combining the benefits of numeric and literal enums. This allows for more flexible and type-safe enum definitions, accommodating both computed and literal values.

Example:

enum Colors {
  Red,
  Green,
  Yellow = "yellow",
  Orange = 4  // computed value must be a number
}

Conclusion

TypeScript's new features promise to revolutionize the way developers write and maintain code. From improved type safety with NoInfer to the functional elegance of groupBy methods, these additions empower developers to build more robust and efficient applications. Stay ahead of the curve by exploring and integrating these new features into your projects.