TypeScript: Modern JavaScript Development

Adding utility functions

We will write several utility functions in lib/game/utils.ts. With flatten, we will transform an array of arrays into one array.

export function flatten<U>(source: U[][]): U[] { 
  return (<U[]>[]).concat(...source); 
} 

With update, we can modify some properties of an object. This is the same function as in previous chapters.

export function update<U extends V, V>(old: U, changes: V): U { 
  const result = Object.create(Object.getPrototypeOf(old)); 
  for (const key of Object.keys(old)) { 
    result[key] = (<any> old)[key]; 
  } 
  for (const key of Object.keys(changes)) { 
    result[key] = (<any> changes)[key]; 
  } 
  return result; 
} 

Next, we will create a function for working with Math.random. randomInt will return a random integer in a certain range ...