task_scheduler_extended

function scheduler(array = [], n = 2) {
    let taskCount = new Map();
    array.forEach((char) => {
        if (taskCount.get(char) !== undefined) {
            taskCount.set(char, taskCount.get(char) + 1)
        } else {
            taskCount.set(char, 1)
        }
    });
    let sortedFrequencies = [...taskCount.entries()].sort((a, b) => b[1] - a[1]);
    let scheduledTasks = [];
    let counter = 0;
    while (taskCount.size !== 0) {
        let task = sortedFrequencies.find(([char, count]) => canBeInserted(scheduledTasks, char));
        if (task === undefined) {
            scheduledTasks.push(null)
        } else {
            let [char, count] = task;
            scheduledTasks.push(char);
            count-1===0?taskCount.delete(char):taskCount.set(char,count-1);
        }
        counter++;
        if (scheduledTasks.length === n + 1) scheduledTasks.shift();
        sortedFrequencies = [...taskCount.entries()].sort((a, b) => b[1] - a[1]);
    }
    return counter;
}

function canBeInserted(list = [], element = '') {
    return list.indexOf(element) === -1
}