disallow specified identifiers (id-blacklist)

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

Bad names can lead to hard-to-decipher code. Generic names, such as data, don’t infer much about the code and the values it receives. This rule allows you to configure a blacklist of bad identifier names, that you don’t want to see in your code.

Rule Details

This rule disallows specified identifiers in assignments and function definitions.

This rule will catch blacklisted identifiers that are:

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

It will not catch blacklisted 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-blacklist": ["error", "data", "err", "e", "cb", "callback"]
}

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

/*eslint id-blacklist: ["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-blacklist: ["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 are happy for identifiers to be named freely.

Version

This rule was introduced in ESLint 2.0.0-beta.2.

Resources

• Rule source
• Documentation source