Run Tasks in Batch

batch.ts

interface Task {
    (): void
}

interface IdleCallback {
    timeRemaining(): number
}

declare function requestIdleCallback(cb: (id: IdleCallback) => void): number

function batch() {
    const taskQueue = new Array<Task>()
    let scheduled = false

    function run(id: IdleCallback) {
        scheduled = false
        while (id.timeRemaining() > 0 && taskQueue.length > 0) {
            const task = taskQueue.shift()
            if (task) task()                        
        }
        schedule()
    }
    function schedule() {
        if (!scheduled && taskQueue.length > 0) {
            scheduled = true
            requestIdleCallback(run)
        }
    }
    return (task: Task) {
        taskQueue.push(task)
        schedule()
    }
}