value

• value(subject: SubjectLike): ValueConstructed<T, S>

• Extracts a property value from the given subject with the given Javascript type. This is a typesafe cast which will not perform type coercion e.g. strings to numbers.

  Per m-ld data semantics, a single value in a field is equivalent to a singleton set (see example), and will also cast successfully to a singleton array.

  Examples:

  new JsProperty('name', JsType.for(String)).value({ name: 'Fred' }); // => 'Fred'
  new JsProperty('name', JsType.for(Number)).value({ name: 'Fred' }); // => throws TypeError
  new JsProperty('name', JsType.for(Set, String)).value({ name: 'Fred' }); // => Set(['Fred'])
  new JsProperty('age', JsType.for(Set)).value({ name: 'Fred' }, 'age'); // => Set([])
  new JsProperty('shopping', JsType.for(Array, String)).value({
    shopping: { '@list': ['Bread', 'Milk'] }
  }); // => ['Bread', 'Milk']
  new JsProperty('birthday', JsType.for(Date)).value({
    birthday: {
      '@value': '2022-01-08T16:49:43.572Z',
      '@type': 'http://www.w3.org/2001/XMLSchema#dateTime'
    }
  }); // => Javascript Date
  

  throws

  TypeError if the given property does not have the correct type

  Parameters

  • subject: SubjectLike

    the subject to inspect

  Returns ValueConstructed<T, S>