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noExcessiveCognitiveComplexity (since v1.0.0)

Diagnostic Category: lint/complexity/noExcessiveCognitiveComplexity

Sources:

Disallow functions that exceed a given Cognitive Complexity score.

The more complexity a function contains, the harder it is to understand later on.

Reducing complexity helps to make code more maintenable, both by making it easier to understand as well as by reducing chances of accidental side-effects when making changes.

This rule calculates a complexity score for every function and disallows those that exceed a configured complexity threshold (default: 15).

The complexity score is calculated based on the Cognitive Complexity algorithm: https://redirect.sonarsource.com/doc/cognitive-complexity.html

Examples

Section titled Examples

Invalid

Section titled Invalid
function tooComplex() {
    for (let x = 0; x < 10; x++) {
        for (let y = 0; y < 10; y++) {
            for (let z = 0; z < 10; z++) {
                if (x % 2 === 0) {
                    if (y % 2 === 0) {
                        console.log(x > y ? `${x} > ${y}` : `${y} > ${x}`);
                    }
                }
            }
        }
    }
}
complexity/noExcessiveCognitiveComplexity.js:1:10 lint/complexity/noExcessiveCognitiveComplexity ━━━━━━━━━━

  ⚠ Excessive complexity detected.
  
  > 1 │ function tooComplex() {
      │          ^^^^^^^^^^
    2 │     for (let x = 0; x < 10; x++) {
    3 │         for (let y = 0; y < 10; y++) {
  
  ℹ Please refactor this function to reduce its complexity score from 21 to the max allowed complexity 15.

Options

Section titled Options

Allows to specify the maximum allowed complexity.

{
    "//": "...",
    "options": {
        "maxAllowedComplexity": 15
    }
}

The allowed values range from 1 through 254. The default is 15.

Section titled Related links