queue.isEnqueued(fn)

Returns boolean true/false if the task fn is in the queue.

Sometimes, it's necessary for a task to be immediately invoked. For example, an observation might depend on another observation currently in the queue. If this happens, the queued task can be run immediately.

const task = function task() {
    console.log( "taskA" );
};

priorityQueue.enqueue( task, null, [], { priority: 5 } );
priorityQueue.isEnqueued( task ); //-> true