PWA Tricks

A collection of useful tricks for PWAs (Progressive Web Apps) and Chrome Pseudo-PWA

Change Starting URL of PWA in Chrome

Sometimes PWAs don't behave in an ideal manner, such as in the following cases:

Google Calendar doesn't allow for multiple Pseudo-PWA shortcuts to different accounts
LinkedIn Messaging will show an ugly black bar if you navigate to another message
Some PWAs may not start on the correct URL

In these cases it can be helpful to change the start_url in the web app manifest for the PWA.

Solution 1: Add an Inline Web App Manifest

Before you install or create the shortcut for the PWA, add a web app manifest with your chosen start_url to the page:

Copy the JavaScript below
On the page of the application, open the Chrome DevTools (right click anywhere on the page and select "Inspect")
Go to the Console tab and paste the copied JavaScript
Modify the URL if necessary to whatever URL you are trying to create an app for (this example is for creating a second Google Calendar Pseudo-PWA)
Hit return to run the JavaScript

const startUrl = 'https://calendar.google.com/calendar/u/1/r';

const unsanitizedHtmlPolicy = trustedTypes.createPolicy('unsanitizedHtml', {
  createHTML: (htmlString) => htmlString,
});

document.head
  .querySelector(':first-child')
  .insertAdjacentHTML(
    'beforebegin',
    unsanitizedHtmlPolicy.createHTML(
      `<link rel="manifest" href='data:application/manifest+json,{"start_url":"${startUrl}"}' />`,
    ),
  );

Once you have done this, you can install the PWA as normal.

Or, if you need to create a shortcut for a pseudo-PWA:

Click on the three dots menu > More Tools > Create Shortcut
Check "Open as window" and select "Create"

Solution 2: Editing Existing Manifest, Security Restriction Workarounds

Inline web app manifests may not work - either if the page already specifies a manifest or if the Content Security Policy directive manifest-src or trusted-types has been set - potentially also returning an error like this:

Refused to load manifest from 'data:application/manifest+json,...' because it violates the following Content Security Policy directive: "manifest-src 'self'".

To get around this, two additional options:

A) Manually Edit HTML

Switch to the Elements tab of the Chrome DevTools and manually edit the HTML to match the manifest in the JavaScript in Solution 1 above

B) Chrome Local Overrides

Use Chrome Local Overrides to modify the start_url in the Web App Manifest, as in the guides below.

Both of the options for this below require Local Overrides to be set up, so do this first:

Open the Sources tab in the Chrome DevTools. If you have not used overrides before, you will need to set them up:
- Switch to the Overrides 2nd-level tab (you may need to find it in the » menu)
- If you Create a new folder in your projects or Documents folder called chrome-overrides
- Click on ＋ Select folder for overrides and select the folder you created
- Confirm any prompts at the top of the browser asking for access to the folder
Refresh the page.

With an Existing Manifest

If there is an existing manifest on the page (document.querySelectorAll('link[rel="manifest"]').length returns 1), then you can modify it like this:

Locate and expand the <head> element under Elements in the Chrome DevTools and locate the link element with rel="manifest". Note the file path in href.
Go to the Sources tab and select the Page tab. Locate the web app manifest corresponding to the file path you noted earlier. Right click and select Save for overrides:
Now the web app manifest is editable! Make your changes to start_url or anything else that you need, save the file and reload the page
The updated web app manifest has now been loaded, and you can install or create a shortcut to the PWA as normal 🙌
You can now remove the overrides (right click on the folder with the domain name -> Delete all overrides)

Without a Manifest

If there isn't yet a manifest on the page (document.querySelectorAll('link[rel="manifest"]').length returns 0), then you can add one like this:

Locate and expand the <head> element under Elements in the Chrome DevTools. Right click on the <head> element and select Edit as HTML. Copy and paste the following code inside the head tag, at the beginning (before all other elements):
```
<link rel="manifest" href="/manifest-temp-pwa-tricks-0123456789.json" />
```
This will trigger a network request to that file. Go to the Network tab, locate the request entry, right-click on it and select Save for overrides
Now the web app manifest is editable! Make your changes to start_url or anything else that you need and save the file.
Reload the page and do step 1 again - edit the <head> and add the link to the newly-created manifest
The updated web app manifest has now been loaded, and you can install or create a shortcut to the PWA as normal 🙌
You can now remove the overrides (right click on the folder with the domain name -> Delete all overrides)

Chrome Pseudo-PWAs

Chrome Pseudo-PWAs (aka shortcuts in new windows) can be created for any website or web application, and behave similarly to full desktop applications on your computer (see https://twitter.com/karlhorky/status/1127884049073233920).