tabs.moveInSuccession()

Modifies the succession relationship for a group of tabs.

Using the tabs API, a tab can be assigned a successor tab in the same window. If tab B is the successor of tab A, and tab A is closed while it is the active tab, tab B will be activated next. If tab A doesn't have a successor, then the browser is free to determine which tab to activate next. If tab B is the successor of tab A, then tab A is called a predecessor of tab B. A tab can have at most one successor, but it can have any number of predecessors. A tab cannot take itself or a tab in a different window as a successor.

All tabs start out with no successor; tabs only get a successor if assigned one by a WebExtension. However, the browser must not orphan a tab in a succession relationship with other tabs, if possible: if tab B is the successor of tab A, and tab C is the successor of tab B, and B is closed (or moved to another window), then tab A will take tab C as its successor. Preventing C from being orphaned in this way is called moving a tab (B) from its line of succession.

tabs.moveInSuccession() takes an array of tab IDs, and moves all of those tabs from their lines of succession. It then makes each tab the successor of the previous tab in the array, forming a chain. It can optionally set the successor of the last tab in the chain to an anchor tab, which is not moved from its line of succession. Additional options can control whether the tab chain is "prepended" or "appended" to the anchor tab, and whether the operation acts like a linked-list insert.

While the successor tab can be assigned with tabs.update(), it is often desirable to use tabs.moveInSuccession() to change successors, even if only a single tab is having its successor assigned. The difference is that browser.tabs.moveInSuccession([a], b) moves tab a from its line of succession, so any predecessors of a will adopt a's previous successor; whereas if browser.tabs.update(a, {successorTabId: b}) is used instead, tab a may continue to be the successor of other tabs, which could be unexpected. Another advantage of tabs.moveInSuccession() is that all of the succession changes happen atomically, without having to worry about races between calls to tabs.update() and tabs.get() and other operations like the user closing a tab.