disallow specified identifiers (id-denylist)

"There are only two hard things in Computer Science: cache invalidation and naming things." — Phil Karlton

Generic names can lead to hard-to-decipher code. This rule allows you to specify a deny list of disallowed identifier names to avoid this practice.

Rule Details

This rule disallows specified identifiers in assignments and function definitions.

This rule will catch disallowed identifiers that are:

• variable declarations
• function declarations
• object properties assigned to during object creation

It will not catch disallowed identifiers that are:

• function calls (so you can still use functions you do not have control over)
• object properties (so you can still use objects you do not have control over)

Options

The rule takes one or more strings as options: the names of restricted identifiers.

For example, to restrict the use of common generic identifiers:

{
    "id-denylist": ["error", "data", "err", "e", "cb", "callback"]
}

Examples of incorrect code for this rule with sample "data", "callback" restricted identifiers:

/*eslint id-denylist: ["error", "data", "callback"] */

var data = {...};

function callback() {
    // ...
}

element.callback = function() {
    // ...
};

var itemSet = {
    data: [...]
};

Examples of correct code for this rule with sample "data", "callback" restricted identifiers:

/*eslint id-denylist: ["error", "data", "callback"] */

var encodingOptions = {...};

function processFileResult() {
    // ...
}

element.successHandler = function() {
    // ...
};

var itemSet = {
    entities: [...]
};

callback(); // all function calls are ignored

foo.callback(); // all function calls are ignored

foo.data; // all property names that are not assignments are ignored

When Not To Use It

You can turn this rule off if you do not want to restrict the use of certain identifiers.

Version

This rule was introduced in ESLint 7.4.0.

Resources

• Rule source
• Documentation source