Let's work with the Workbook object in JavaScript.

Workbook Object.EXCEL.yaml

name: Workbook Object
description: Let's work with the Workbook object in JavaScript.
host: EXCEL
api_set: {}
script:
  content: |
    $("#run1").click(() => tryCatch(workbookObjects));
    $("#run2").click(() => tryCatch(myWorksheetsColl));

    async function workbookObjects() {
      await Excel.run(async (context) => {
        // grab the workbook
        const xlWorkbook = context.workbook;

        // grab the chart
        const xlChart = xlWorkbook.getActiveChart();

        // grab the PivotTable
        //const xlPivotTable = xlWorkbook.pivotTables.getItem('PivotTable1');

        // grab the chart name property and load it.
        //xlPivotTable.load(["name", "dataHierarchies"]);

        // grab the chart name property and load it.
        xlChart.load(["name", "chartType", "id"]);

        // sync it
        await context.sync();

        // print the results
        console.log(`The chart name is ${xlChart.name}`);
        console.log(`The chart type is ${xlChart.chartType}`);
        console.log(`The chart ID is ${xlChart.id}`);

        // print the results
        //console.log(`The Pivot Table name is ${xlPivotTable.name}`);
        //console.log(`The Pivot table has ${xlPivotTable.dataHierarchies} hierarchies`);
      });
    }

    async function myWorksheetsColl() {
      await Excel.run(async (context) => {
        // grab the workbook
        const xlWorkbook = context.workbook;

        // Define the worksheets collection
        const xlWorksheets = xlWorkbook.worksheets;

        // define the properties we want to load
        xlWorkbook.load(["properties/"]);

        // define the properties we want to load
        xlWorksheets.load(["name", "items", "id"]);

        // get the count, this requires a load.
        let worksheetCount = xlWorksheets.getCount();

        // sync the pivot table properties, the worksheet properties, and the getCount.
        await context.sync();

        // let's loop through all the worksheets, using a "For Each" loop
        for (let i in xlWorksheets.items) {
          console.log(xlWorksheets.items[i].name);
        }

        // let's loop through all the worksheets using a "For" loop
        for (let i = 0; i < worksheetCount.value; i++) {
          console.log(xlWorksheets.items[i].id);
        }

        // print some properties.
        console.log(xlWorkbook.properties.lastAuthor);
        console.log(xlWorkbook.properties.creationDate);

        console.log(Excel.CalculationState);
      });
    }

    /** Default helper for invoking an action and handling errors. */
    async function tryCatch(callback) {
      try {
        await callback();
      } catch (error) {
        // Note: In a production add-in, you'd want to notify the user through your add-in's UI.
        console.error(error);
      }
    }
  language: typescript
template:
  content: |-
    <button id="run1" class="ms-Button">
        <span class="ms-Button-label">Run One</span>
    </button>

    <button id="run2" class="ms-Button">
        <span class="ms-Button-label">Run Two</span>
    </button>
  language: html
style:
  content: |-
    section.samples {
        margin-top: 20px;
    }

    section.samples .ms-Button, section.setup .ms-Button {
        display: block;
        margin-bottom: 5px;
        margin-left: 20px;
        min-width: 80px;
    }
  language: css
libraries: |
  https://appsforoffice.microsoft.com/lib/1/hosted/office.js
  @types/office-js

  [email protected]/dist/css/fabric.min.css
  [email protected]/dist/css/fabric.components.min.css

  [email protected]/client/core.min.js
  @types/core-js

  @microsoft/[email protected]/dist/office.helpers.min.js
  @microsoft/[email protected]/dist/office.helpers.d.ts

  [email protected]
  @types/[email protected]