How to force auto complete in app script editor for ambiguous variables?

function onEdit(e)
  e... //I want auto completion
  var range = e.range();
  e.... //I want auto completion
}

How to force auto completion on a variable such as in onEdit, is there a way to explicitly specify what type e is for the purposes of auto completion?

1. how to see what the datatype of e is.
2. how to explicitly specify e is that datatype for auto completion in the google app script editor.

In the new Apps Script IDE you can use JSDoc for auto completion with built-in types.

/**
 * Clears the content of the range, leaving the formatting intact.
 * @param {SpreadsheetApp.Range} range The range to clear the content
 * @return {SpreadsheetApp.Range} This range, for chaining.
 */
function clearContent(range) {
  range.clearContent()
}

The Event object doesn't appear to have a built-in declaration, but you can always create your own.

/**
 * @typedef {Object} onEditEvent 
 * @property {ScriptApp.AuthMode} authMode A value from the ScriptApp.AuthMode enum.
 * @property {string} oldValue Cell value prior to the edit, if any. Only available if the edited range is a single cell. 
 *                    Will be undefined if the cell had no previous content.
 * @property {SpreadsheetApp.Range} range A Range object, representing the cell or range of cells that were edited.
 * @property {SpreadsheetApp.Spreadsheet} source A Spreadsheet object, representing the Google Sheets file to which the script is bound.
 * @property {string} triggerUid ID of trigger that produced this event (installable triggers only).
 * @property {User} user A User object, representing the active user, if available (depending on a complex set of security restrictions).
 * @property {string} value New cell value after the edit. Only available if the edited range is a single cell.
 */


/**
 * @param {onEditEvent} e The onEdit event.
 */
function onEdit(e) {
  e... // type to show autocomplete 

}