Disallow specific global variables (no-restricted-globals)

Disallowing usage of specific global variables can be useful if you want to allow a set of global variables by enabling an environment, but still want to disallow some of those.

For instance, early Internet Explorer versions exposed the current DOM event as a global variable event, but using this variable has been considered as a bad practice for a long time. Restricting this will make sure this variable isn’t used in browser code.

Rule Details

This rule allows you to specify global variable names that you don’t want to use in your application.

Options

This rule takes a list of strings, where each string is a global to be restricted:

{
    "rules": {
        "no-restricted-globals": ["error", "event", "fdescribe"]
    }
}

Alternatively, the rule also accepts objects, where the global name and an optional custom message are specified:

{
    "rules": {
        "no-restricted-globals": [
            "error",
            {
                "name": "event",
                "message": "Use local parameter instead."
            },
            {
                "name": "fdescribe",
                "message": "Do not commit fdescribe. Use describe instead."
            }
        ]
    }
}

Examples of incorrect code for sample "event", "fdescribe" global variable names:

/*global event, fdescribe*/
/*eslint no-restricted-globals: ["error", "event", "fdescribe"]*/

function onClick() {
    console.log(event);
}

fdescribe("foo", function() {
});

Examples of correct code for a sample "event" global variable name:

/*global event*/
/*eslint no-restricted-globals: ["error", "event"]*/

import event from "event-module";

/*global event*/
/*eslint no-restricted-globals: ["error", "event"]*/

var event = 1;

Examples of incorrect code for a sample "event" global variable name, along with a custom error message:

/*global event*/
/* eslint no-restricted-globals: ["error", { name: "error", message: "Use local parameter instead." }] */

function onClick() {
    console.log(event);    // Unexpected global variable 'event'. Use local parameter instead.
}

Version

This rule was introduced in ESLint 2.3.0.

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