tags-toy.js

const _ = require('lodash');

const tags = (initialValue) => {
  if ((typeof initialValue !== 'object' || Array.isArray(initialObject) === true)
    || (typeof initialValue !== 'undefined')) throw new Error('initial value must be undefined or an object');
  
  const _tags = initialValue || {};
  return {
    addTag: (name, value) => {
      if (typeof value === 'string' && value.length > 0) return tags(_.set(_tags, name, value));
      else return tags(_tags);
    },
    value: () => {
      return _tags;
    }
  }
}

let t = tags().addTag("henlo", "fren").addTag("configured", true).value();

i was creating an object and needed to assign to a value an object which processed data and did not define fields upon the child object for data fields which did not meet certain criteria. rather than a mutable solution, if (x) { object[key] = value; }, i instead opted for this immutable "toy".