tcomb

import t from 'tcomb'; // A type-checked function demonstrating basic validation function sum(a, b) { t.Number(a); // Runtime check: 'a' must be a Number t.Number(b); // Runtime check: 'b' must be a Number return a + b; } try { sum(1, 's'); // This will throw an error } catch (e) { console.error(`Caught error for sum(1, 's'): ${e.message}`); } // Define a custom refined type (Integer) const Integer = t.refinement(t.Number, (n) => n % 1 === 0, 'Integer'); // Define a structured object (a 'struct') for a Person const Person = t.struct({ name: t.String, // required string surname: t.maybe(t.String), // optional string (can be null or undefined) age: Integer, // required integer (using our custom Integer type) tags: t.list(t.String) // a list of strings }, 'Person'); // Add a method to the struct's prototype (as you would with a class) Person.prototype.getFullName = function () { return `${this.name} ${this.surname ?? ''}`.trim(); }; let personInstance; try { personInstance = Person({ name: 'Guido', age: 42, tags: ['developer', 'js'] }); console.log(`Created person: ${personInstance.getFullName()}`); } catch (e) { console.error(`Caught error creating person: ${e.message}`); } // Attempt to create a person with missing required fields try { Person({ surname: 'Canti' }); // This will throw an error for missing 'name' and 'age' } catch (e) { console.error(`Caught error for invalid person creation: ${e.message}`); } // Update an immutable instance using t.update const updatedPerson = Person.update(personInstance, { name: { $set: 'Giuliano' }, // Change name age: { $set: 43 }, // Change age tags: { $push: ['opensource'] } // Add a tag }); console.log(`Updated person: ${updatedPerson.getFullName()}, Age: ${updatedPerson.age}, Tags: ${updatedPerson.tags.join(', ')}`);