max-nested-callbacks

Enforce a maximum depth that callbacks can be nested

Many JavaScript libraries use the callback pattern to manage asynchronous operations. A program of any complexity will most likely need to manage several asynchronous operations at various levels of concurrency. A common pitfall that is easy to fall into is nesting callbacks, which makes code more difficult to read the deeper the callbacks are nested.

foo(function () {
 bar(function () {
 baz(function() {
 qux(function () {

 });
 });
 });
});
1
2
3
4
5
6
7
8
9

Rule Details

This rule enforces a maximum depth that callbacks can be nested to increase code clarity.

Options

This rule has a number or object option:

"max" (default 10) enforces a maximum depth that callbacks can be nested

Deprecated: The object property maximum is deprecated; please use the object property max instead.

max

Examples of incorrect code for this rule with the { "max": 3 } option:

Open in Playground

/*eslint max-nested-callbacks: ["error", 3]*/

foo1(function() {
 foo2(function() {
 foo3(function() {
 foo4(function() {
 // Do something
 });
 });
 });
});
1
2
3
4
5
6
7
8
9
10
11

Examples of correct code for this rule with the { "max": 3 } option:

Open in Playground

/*eslint max-nested-callbacks: ["error", 3]*/

foo1(handleFoo1);

function handleFoo1() {
 foo2(handleFoo2);
}

function handleFoo2() {
 foo3(handleFoo3);
}

function handleFoo3() {
 foo4(handleFoo4);
}

function handleFoo4() {
 foo5();
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

URL: https://eslint.org/docs/latest/rules/max-nested-callbacks