Limit Cyclomatic Complexity (complexity)

Cyclomatic complexity measures the number of linearly independent paths through a program’s source code. This rule allows setting a cyclomatic complexity threshold.

function a(x) {
    if (true) {
        return x; // 1st path
    } else if (false) {
        return x+1; // 2nd path
    } else {
        return 4; // 3rd path
    }
}

Rule Details

This rule is aimed at reducing code complexity by capping the amount of cyclomatic complexity allowed in a program. As such, it will warn when the cyclomatic complexity crosses the configured threshold (default is 20).

The following patterns are considered problems:

/*eslint complexity: [2, 2]*/

function a(x) {               /*error Function 'a' has a complexity of 3.*/
    if (true) {
        return x;
    } else if (false) {
        return x+1;
    } else {
        return 4; // 3rd path
    }
}

The following patterns are not considered problems:

/*eslint complexity: [2, 2]*/

function a(x) {
    if (true) {
        return x;
    } else {
        return 4;
    }
}

When Not To Use It

If you can’t determine an appropriate complexity limit for your code, then it’s best to disable this rule.

Further Reading

Version

This rule was introduced in ESLint 0.0.9.

Resources