Web Apps

If you build a user interface for a script, you can publish the script as a web app. For example, a script that lets users schedule appointments with members of a support team would best be presented as a web app so that users can access it directly from their browsers.

Both standalone scripts and scripts bound to Google Workspace applications can be turned into web apps, so long as they meet the requirements below.

Requirements for web apps

A script can be published as a web app if it meets these requirements:

• It contains a doGet(e) or doPost(e) function.
• The function returns an HTML service HtmlOutput object or a Content service TextOutput object.

Request parameters

When a user visits an app or a program sends the app an HTTP GET request, Apps Script runs the function doGet(e). When a program sends the app an HTTP POST request, Apps Script runs doPost(e) instead. In both cases, the e argument represents an event parameter that can contain information about any request parameters. The structure of the event object is shown in the table below:

name=alice&n=1&n=2

{"name": "alice", "n": "1"}

{"name": ["alice"], "n": ["1", "2"]}

332

332

text/csv

Alice,21

postData

For instance, you could pass parameters such as username and age to a URL as shown below:

https://script.google.com/.../exec?username=jsmith&age=21

Then, you can display the parameters like so:

function doGet(e) {
  var params = JSON.stringify(e);
  return HtmlService.createHtmlOutput(params);
}

In the above example, doGet(e) returns the following output:

{
  "queryString": "username=jsmith&age=21",
  "parameter": {
    "username": "jsmith",
    "age": "21"
  },
  "contextPath": "",
  "parameters": {
    "username": [
      "jsmith"
    ],
    "age": [
      "21"
    ]
  },
  "contentLength": -1
}

Deploy a script as a web app

To deploy a script as a web app, follow these steps:

You can share the web app URL with those you would like to use your app, provided you have granted them access.

Test a web app deployment

Permissions

The permissions for a web app differ depending how you choose to execute the app:

• Execute the app as me—In this case, the script always executes as you, the owner of the script, no matter who accesses the web app.
• Execute the app as user accessing the web app—In this case, the script runs under the identity of the active user using the web app. This permission approach causes the web app to show the email of the script owner when the user authorizes access.

Embedding your web app in Google Sites

You can also embed web apps in both the classic and new versions of Google Sites.

Embedding a web app in new Sites

In order to embed a web app, it must first be deployed. You also need the Deployed URL from the Deploy dialog.

To embed a web app into a new Sites page, follow these steps:

1. Open the Sites page where you'd like to add the web app.
2. Select Insert > Embed URL.
3. Paste in the web app URL and then click ADD.

The web app appears in a frame in the page's preview. When you publish the page, your site viewers may need to authorize the web app before it executes normally. Unauthorized web apps present authorization prompts to the user.

Embedding a web app in classic Sites

You can bind a script to a classic Google Site in much the same way as a you can bind a script to a Google Doc or Sheet. To create a bound script, visit your site, click the gear icon , then select Manage site. On the Manage Site page, click Apps Scripts in the left nav, then the Add new script button. This opens a new script in the Apps Script editor, where you can code and deploy your web app.

You can also embed your web app in a page. You can bind the web app to the Site or you can use any web app that you have the URL for. To embed a web app into a Google Sites page, follow the steps below:

1. Open an existing Site for which you have edit access or create a new Site.
2. Navigate to the page in your Site where you want to embed the web app.
3. Click the edit icon, and then Insert > Google Apps Script.
4. Choose the script from the list that represents your web app. If your web app is not bound to this Site, you can paste in the web app URL instead.
5. Click the Select button, choose the desired options from the next dialog, and click Save.
6. Save your changes to the page and then you should see your web app embedded in your Sites page.

Web Apps and Browser History

It can be desirable to have an Apps Script web app simulate a multi-page application, or one with a dynamic UI controlled via URL parameters. In order to do this well, you can define a state object to represent the app's UI or page, and push the state into the browser history as the user navigates your app. You can also listen to history events so that your web app displays the correct UI when the user navigates back and forth with the browser buttons. By querying the URL parameters at load time, you can have your app dynamically build its UI based on those parameters, allowing the user to start the app in a particular state.

Apps Script provides two asynchronous client-side JavaScript APIs to assist with creating web apps that are linked to the browser history:

• google.script.history provides methods to allow dynamic response to browser history changes. This includes: pushing states (simple Objects you can define) onto the browser history, replacing the top state in the history stack, and setting a listener callback function to respond to history changes.

• google.script.url provides the means to retrieve the current page's URL parameters and URL fragment, if they are present.

These history APIs are only available to web apps. They are not supported for sidebars, dialogs or add-ons. This functionality is also not recommended for use in web apps embedded in a Google Sites.