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max-classes-per-file

Enforce a maximum number of classes per file

Files containing multiple classes can often result in a less navigable and poorly structured codebase. Best practice is to keep each file limited to a single responsibility.

Rule Details

This rule enforces that each file may contain only a particular number of classes and no more.

Examples of incorrect code for this rule:

/*eslint max-classes-per-file: "error"*/

class Foo {}
class Bar {}

Examples of correct code for this rule:

/*eslint max-classes-per-file: "error"*/

class Foo {}

Options

This rule may be configured with either an object or a number.

If the option is an object, it may contain one or both of:

  • ignoreExpressions: a boolean option (defaulted to false) to ignore class expressions.
  • max: a numeric option (defaulted to 1) to specify the maximum number of classes.

For example:

{
"max-classes-per-file": ["error", 1]
}
{
"max-classes-per-file": [
"error",
{ "ignoreExpressions": true, "max": 2 }
]
}

Examples of correct code for this rule with the max option set to 2:

/* eslint max-classes-per-file: ["error", 2] */

class Foo {}
class Bar {}

Examples of correct code for this rule with the ignoreExpressions option set to true:

/* eslint max-classes-per-file: ["error", { ignoreExpressions: true }] */

class VisitorFactory {
forDescriptor(descriptor) {
return class {
visit(node) {
return `Visiting ${descriptor}.`;
}
};
}
}

Version

This rule was introduced in ESLint v5.0.0-alpha.3.

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