Function lazyRecord

Creates a read-only non-extensible record with properties based on the given definitions. If the property in the definition is a function, it will only be executed once lazily, i.e. on the first evaluation of the respective property.

Trying to change or add a property will result in both compiler and runtime errors.

Example

let id = 0;
const getId = () => ++id;
// mix lazy functions with plain values
const obj = lazyRecord({ id: getId, name: 'TypeScript' });
expect(id).toBe(0); // getId not called yet, so global id is still 0
expect(obj.id).toBe(1); // calls getId once
expect(obj.id).toBe(1); // won't be called again and value stays the same
expect(id).toBe(1); // getId only called once, so global id is still 1