dinamic-js-mixins.js

inject(mixin) {
    if (Array.isArray(mixin)) {
      for(let i in mixin) {
        this.inject(mixin[i]);
      }
      return;
    } else if ('object' !== typeof mixin) {
      throw Error('Invalid mixin');
    }

    for (let prop in mixin) {
      if (!mixin.hasOwnProperty(prop)) { continue; }
      if ('function' === typeof mixin[prop]) {
        if ('undefined' !== typeof Object.getPrototypeOf(this)[prop]) {
          throw Error('Property ' + prop + ' already exists at prototype!');
        }
        Object.getPrototypeOf(this)[prop] = () => mixin[prop].apply(this, arguments);
      } else {
        if ('undefined' !== typeof this[prop]) {
          throw Error('Property ' + prop + ' already exists as this!');
        }

        Object.defineProperty(this, 'prop', {
          get: function() {
            return mixin[prop];
          }
        });
      }
    }
  }

static-js-mixins.js

use(mixin) {
    if (Array.isArray(mixin)) {
      for(let i in mixin) {
        this.use(mixin[i]);
      }
      return;
    } else if ('object' !== typeof mixin) {
      throw Error('Invalid mixin');
    }

    for (let prop in mixin) {
      if (!mixin.hasOwnProperty(prop)) { continue; }
      if ('function' === typeof mixin[prop]) {
        if ('undefined' !== typeof Object.getPrototypeOf(this)[prop]) {
          throw Error('Property ' + prop + ' already exists at prototype!');
        }
        Object.getPrototypeOf(this)[prop] = mixin[prop];
      } else {
        if ('undefined' !== typeof this[prop]) {
          throw Error('Property ' + prop + ' already exists as this!');
        }
        this[prop] = mixin[prop];
      }
    }
  }