Custom Lovelace card for displaying Amazon Deliveries via check_mail command line sensor in Home Assistant

deliveries_card.js

class DeliveriesCard extends HTMLElement {
  set hass(hass) {

    const entityId = this.config.entity;
    const stateObj = hass.states[entityId];
    const stateStr = stateObj ? stateObj.state : 'unavailable';
    const items = JSON.parse(stateStr);   
    const itemCount = items.length;

    if (!this.content) {
      const card = document.createElement('ha-card');
      card.header = document.createElement('div');
      card.id = "deliveriesHeader";
      card.header.innerHTML = `<ha-icon style="padding-right: 5px;" icon="mdi:truck-fast"></ha-icon> Deliver${itemCount > 1 ? 'ies' : 'y'} Today (${itemCount} item${itemCount > 1 ? 's' : ''})`;
      this.content = document.createElement('div');
      this.content.style.padding = '0px 16px 16px';
      card.appendChild(this.content);
      this.appendChild(card);
    }

    let innerHtml = ``;
    for(let i = 0; i< items.length; i++) { 
       innerHtml = innerHtml + items[i] + '<br />';
    }
    this.content.innerHTML = innerHtml;
  }

  setConfig(config) {
    if (!config.entity) {
      throw new Error('You need to define an entity');
    }
    this.config = config;
  }

  // The height of your card. Home Assistant uses this to automatically
  // distribute all cards over the available columns.
  getCardSize() {
    return 3;
  }
}

customElements.define('deliveries-card', DeliveriesCard);