Create a new snippet from a blank template.

Group_UnGroup_Outline.EXCEL.yaml

name: Group_UnGroup_Outline
description: Playing with Excel API.
host: EXCEL
api_set: {}
script:
  content: |
    $("#groupRow").click(() => tryCatch(groupRow));
    $("#groupCol").click(() => tryCatch(groupCol));
    $("#ungroupRow").click(() => tryCatch(ungroupRow));
    $("#ungroupCol").click(() => tryCatch(ungroupCol));
    $("#showDetailsRow").click(() => tryCatch(showDetailsRow));
    $("#showDetailsCol").click(() => tryCatch(showDetailsCol));
    $("#hideDetailsRow").click(() => tryCatch(hideDetailsRow));
    $("#hideDetailsCol").click(() => tryCatch(hideDetailsCol));

    async function groupRow() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.group("ByRows");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function groupCol() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.group("ByColumns");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function ungroupRow() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.ungroup("ByRows");
        console.log("Your code goes here");
        await context.sync();
      });
    }

    async function ungroupCol() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.ungroup("ByColumns");
        console.log("Your code goes here");
        await context.sync();
      });
    }
    async function ungroupRow() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.ungroup("ByRows");
        console.log("Your code goes here");
        await context.sync();
      });
    }

    async function showDetailsRow() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.showGroupDetails("ByRows");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function showDetailsCol() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.showGroupDetails("ByColumns");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function hideDetailsRow() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.hideGroupDetails("ByRows");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function hideDetailsCol() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        var range = context.workbook.getSelectedRange();
        range.hideGroupDetails("ByColumns");
        console.log("Your code goes here");

        await context.sync();
      });
    }

    async function expandCollapseByIndex() {
      await Excel.run(async (context) => {
        const sheet = context.workbook.worksheets.getActiveWorksheet();
        sheet.expandCollapseRowByIndex(2, 5);
        // ol.load();
        console.log("Your code goes here");

        await context.sync();
      });
    }

    /** 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="groupRow" class="ms-Button">
        <span class="ms-Button-label">Group Rows</span>
    </button>
    <button id="groupCol" class="ms-Button">
        <span class="ms-Button-label">Group Column</span>
    </button>
    <button id="ungroupRow" class="ms-Button">
        <span class="ms-Button-label">Ungroup Rows</span>
    </button>
    <button id="ungroupCol" class="ms-Button">
        <span class="ms-Button-label">Ungroup Columns</span>
    </button>
    <button id="showDetailsRow" class="ms-Button">
        <span class="ms-Button-label">Show Details Row</span>
    </button>
    <button id="showDetailsCol" class="ms-Button">
        <span class="ms-Button-label">Show Details Col</span>
    </button>
    <button id="hideDetailsRow" class="ms-Button">
        <span class="ms-Button-label">Hide Details Row</span>
    </button>
    <button id="hideDetailsCol" class="ms-Button">
        <span class="ms-Button-label">Hide Details Column</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/beta/hosted/office.js
  @types/office-js

  office-ui-fabric-js@1.4.0/dist/css/fabric.min.css
  office-ui-fabric-js@1.4.0/dist/css/fabric.components.min.css

  core-js@2.4.1/client/core.min.js
  @types/core-js

  @microsoft/office-js-helpers@0.7.4/dist/office.helpers.min.js
  @microsoft/office-js-helpers@0.7.4/dist/office.helpers.d.ts

  jquery@3.1.1
  @types/jquery@3.3.1

Instructions:
Add the Script Lab add-in:
Go to Add-ins under Insert tab. Search for Script Lab and add it
Click the Script Lab tab, and click Code
Click Import and attach the link to this gist
Click run