defaultdict.ts

const defaultDict = <T>(defaultValue: T, object = {}): { [key: string]: T } => {
  return new Proxy(object, {
    get(obj, prop) {
      return prop in obj ? obj[prop] : defaultValue;
    },
  });
};

const dict = defaultDict(100);

dict.a = 1;
dict.a++;

dict.b /= 10;

console.log(`結果: ${dict.a}, ${dict.b}, ${dict.c}`);
//=> 結果: 2, 10, 100