Common API - Office.Bindings

addFromNamedItemAsync	M	Creates a binding against a named object in the document.
addFromPromptAsync	M	Create a binding by prompting the user to make a selection on the document.
addFromSelectionAsync	M	Create a binding based on the user's current selection.
document	P	Gets an Office.Document object that represents the document associated with this set of bindings.
getAllAsync	M	Gets all bindings that were previously created.
getByIdAsync	M	Retrieves a binding based on its Name.
releaseByIdAsync	M	Removes the binding from the document.

let myvar: Office.Bindings

For Excel use Excel.Binding instead of Office.Binding
context.workbook.bindings

For Word Bindings - Word API Bindings