noExcessiveNestedCallbacks

JavaScript (and super languages)

Summary

Rule available since: v2.4.14
Diagnostic Category: lint/nursery/noExcessiveNestedCallbacks
This rule doesn’t have a fix.
The default severity of this rule is warning.
Sources:
- Same as max-nested-callbacks

How to configure

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{
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  "linter": {
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    "rules": {
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      "nursery": {
5
        "noExcessiveNestedCallbacks": "error"
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      }
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    }
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  }
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}

Description

Enforce a maximum depth that callbacks can be nested.

Deeply nested callbacks make asynchronous control flow difficult to read and follow. This rule reports callback functions nested beyond the configured limit.

Examples

Invalid

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foo1(function () {
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    foo2(function () {
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        foo3(function () {
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            foo4(function () {
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                foo5(function () {
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                    foo6(function () {});
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                });
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            });
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        });
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    });
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});

code-block.js:6:26 lint/nursery/noExcessiveNestedCallbacks ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ This callback is nested too deeply.
  
    4 │             foo4(function () {
    5 │                 foo5(function () {
  > 6 │                     foo6(function () {});
      │                          ^^^^^^^^^^^^^^
    7 │                 });
    8 │             });
  
  ℹ Callbacks nested 6 levels deep are harder to read and maintain. The configured maximum is 5.
  
  ℹ Extract some callbacks into named functions to reduce nesting.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.

Valid

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foo1(handleFoo1);
2

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function handleFoo1() {
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    foo2(handleFoo2);
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}

Options

max

The maximum callback nesting depth allowed (default: 5).

1
{
2
  "linter": {
3
    "rules": {
4
      "nursery": {
5
        "noExcessiveNestedCallbacks": {
6
          "options": {
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            "max": 3
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          }
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        }
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      }
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    }
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  }
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}

Invalid

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foo1(function () {
2
    foo2(function () {
3
        foo3(function () {
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            foo4(function () {});
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        });
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    });
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});

code-block.js:4:18 lint/nursery/noExcessiveNestedCallbacks ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ This callback is nested too deeply.
  
    2 │     foo2(function () {
    3 │         foo3(function () {
  > 4 │             foo4(function () {});
      │                  ^^^^^^^^^^^^^^
    5 │         });
    6 │     });
  
  ℹ Callbacks nested 4 levels deep are harder to read and maintain. The configured maximum is 3.
  
  ℹ Extract some callbacks into named functions to reduce nesting.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.

Valid

1
foo1(function () {
2
    foo2(function () {
3
        foo3(function () {});
4
    });
5
});

noExcessiveNestedCallbacks

Summary

How to configure

Description

Examples

Invalid

Valid

Options

max

Invalid

Valid

Related links