Provide a graceful loading animation for the LinkField

[maxime-rainville]

Story

As a content author, I want clear feedback from the UI so I can understand what elements are ready to use and what elements are still initialising.

Note

• Ideally just use the existing loading component. People might use the js injector to replace the loading component, so it would be nice if they don't have to replace multiple loading components.

Acceptance criteria

• Linkfield shows the <Loading> component when appropriate
• Have tested using bandwidth restrictor using browser developer tools

Related

• This commit in AnyField how you can provide pre-react-render loading animation
• That's the AnyField animation. Maxime just took the regular loading animation and pop it into the LinkField Box.

PR

• ENH Show loading component during ajax read requests #162

[sabina-talipova]

PR is merged. Close issue.