max-nested-callbacks - ESLint - Pluggable JavaScript Linter (original) (raw)

Enforce a maximum depth that callbacks can be nested

Table of Contents

1. Rule Details
2. Options
   1. max
3. Related Rules
4. Version
5. Further Reading
6. Resources

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 () {

            });
        });
    });
});

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
            });
        });
    });
});

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();
}

Version

This rule was introduced in ESLint v0.2.0.

Further Reading

Resources

• Rule source
• Tests source