JavaScript - Callback Hell

Callback hell is nesting muiltple callbacks within a function where one callback's output is depend on the previous callback.

It is generally refers to an ineffective way of writing asynchronous code.

It makes the code very difficult to understand and maintain.

Example of callback hell

getScore("Virat", (score) => {
    totalScore += score;
    getScore("Sachin", (score) => {
        totalScore += score;
        getScore("Sachin", (score) => {
            totalScore += score;
            printScore(totalScore);
        });
    });
});

We can use promise or async/await to avoid callback hell.