Javascript differences between CRM and D365 CRM

Deprecated Client API	Replacement Client API	Comments
Xrm.Page	Forms: ExecutionContext.getFormContext  Commands: Send it as the PrimaryControl parameter	Use of the Xrm.Page object as a static access to the primary form context is still supported to maintain backward compatibility with the existing scripts. Based on the feedback, we understand that the usage of Xrm.Page is high, and it won’t be removed as soon as some other client API methods listed in this section. We encourage you to use the new way of getting form content where possible. More information: Client API form context Although Xrm.Page is deprecated, parent.Xrm.Page will continue to work in case of HTML web resources embedded in forms as this is the only way to access the form context from the HTML web resource.
Xrm.Page.context	Xrm.Utility.getGlobalContext	Allows access to the global context without going through the form context.
Xrm.Page.context.getQueryStringParameters	formContext.data.attributes	The formContext.data.attributes API will make retrieval of non-entity bound data consistent across entity forms, metadata-driven dialogs, and task-based flows. The data will be a combination of custom values sent using the query string and what was specified in the parameters in the openForm method.
Xrm.Page.context.getTimeZoneOffsetMinutes	globalContext.userSettings.getTimeZoneOffsetMinutes	Moved to globalContext.userSettings
Xrm.Page.context.getUserId	globalContext.userSettings.userId	Moved to globalContext.userSettings
Xrm.Page.context.getUserLcid	globalContext.userSetings.languageId	Moved to globalContext.userSettings
Xrm.Page.context.getUserName	globalContext.userSettings.userName	Moved to globalContext.userSettings
Xrm.Page.context.getUserRoles	globalContext.userSettings.securityRoles	Moved to globalContext.userSettings
Xrm.Page.context.getIsAutoSaveEnabled	globalContext.organizationSettings.isAutoSaveEnabled	Moved to globalContext.organizationSettings
Xrm.Page.context.getOrgLcid	globalContext.organizationSettings.languageId	Moved to globalContext.organizationSettings
Xrm.Page.context.getOrgUniqueName	globalContext.organizationSettings.uniqueName	Moved to globalContext.organizationSettings
Xrm.Page.data.entity.getDataXml	No change in the method, but use "typename" instead of type for lookup attributes.
GridRow.getData	GridRow.data	GridRow is essentially a form context. This change unifies the interface of GridRow with formContext.
GridRowData.getEntity	GridRowData.entity	GridRowData is form data. This change unifies the interface of GridRowData with formContextData.
Xrm.Mobile.offline	Xrm.WebApi.offline	Moved the offline-related methods under Xrm.WebApi.offline
parent.Xrm		Earlier: An HTML web resource may interact with the Xrm.Page or Xrm.Utility objects within the form by using parent.Xrm.Page or parent.Xrm.Utility.  Now: parent.Xrm.* will work if the HTML web resource is loaded in a form container. It won't work for HTML web resources that are stand alone, or referenced from the site map or any other places.
addOnKeyPress	Use a custom control
removeOnKeyPress	Use a custom control
showAutoComplete	Use a custom control and corresponding UI
hideAutoComplete	Use a custom control and corresponding UI
Xrm.Utility.alertDialog	Xrm.Navigation.openAlertDialog	The new signature is consistent with other APIs (openForm) and takes a new set of parameters for flexibility.
Xrm.Utility.confirmDialog	Xrm.Navigation.openConfirmDialog	The new signature is consistent with other APIs (openForm) and takes a new set of parameters for flexibility.
Xrm.Utility.isActivityType	Xrm.Utility.getEntityMetadata	The isActivityType method is synchronous so it was suitable for ribbon rules. However, the replacement method, getEntityMetadata, is asynchronous, and is not suitable for ribbon rules.
Xrm.Utility.openEntityForm	Xrm.Navigation.openForm	Moving navigation actions to Xrm.Navigation
Xrm.Utility.openQuickCreate	Xrm.Navigation.openForm	Moving navigation actions to Xrm.Navigation
Xrm.Utility.openWebResource	Xrm.Navigation.openWebResource	Moving navigation actions to Xrm.Navigation  Note: This API returns VOID in Unified Interface.

Source : https://docs.microsoft.com/en-us/dynamics365/get-started/whats-new/customer-engagement/important-changes-coming#some-client-apis-are-deprecated