environment: "staging" on SukiAuthManager (not isTestMode on init). This page shows a React example; the same SukiAuthManager settings work with initialize() in JavaScript.
Code example
The example below points the SDK at staging and turns on debug logging.React
Web SDK v2 used
isTestMode: true on init options for the same idea. Web SDK v3 uses environment on SukiAuthManager instead. See Migrating to Web SDK v3 and InitOptions.