Require correct usage of hashbang (`n/hashbang`)

💼 This rule is enabled in the following configs: 🟢 recommended-module, ✅ recommended-script.

🔧 This rule is automatically fixable by the --fix CLI option.

When we make a CLI tool with Node.js, we add bin field to package.json, then we add a hashbang the entry file. This rule suggests correct usage of hashbang.

📖 Rule Details

This rule looks up package.json file from each linting target file. Starting from the directory of the target file, it goes up ancestor directories until found.

If package.json was not found, this rule does nothing.

This rule checks bin field of package.json, then if a target file matches one of bin files, it checks whether or not there is a correct hashbang. Otherwise it checks whether or not there is not a hashbang.

The following patterns are considered problems for files in bin field of package.json:

console.log("hello"); /*error This file needs hashbang "#!/usr/bin/env node".*/

#!/usr/bin/env node  /*error This file must not have Unicode BOM.*/
console.log("hello");
// If this file has Unicode BOM.

#!/usr/bin/env node  /*error This file must have Unix linebreaks (LF).*/
console.log("hello");
// If this file has Windows' linebreaks (CRLF).

The following patterns are considered problems for other files:

#!/usr/bin/env node   /*error This file needs no hashbang.*/
console.log("hello");

The following patterns are not considered problems for files in bin field of package.json:

#!/usr/bin/env node
console.log("hello");

The following patterns are not considered problems for other files:

console.log("hello");

Options

{
    "n/hashbang": ["error", {
        "convertPath": null,
        "ignoreUnpublished": false,
        "additionalExecutables": [],
        "executableMap": {
            ".js": "node"
        }
    }]
}

convertPath

This can be configured in the rule options or as a shared setting settings.convertPath. Please see the shared settings documentation for more information.

ignoreUnpublished

Allow for files that are not published to npm to be ignored by this rule.

additionalExecutables

Mark files as executable that are not referenced by the package.json#bin property

executableMap

Allow for different executables to be used based on file extension. This is in the form "{extension}": "{binaryName}".

{
    ".js": "node",
    ".ts": "ts-node"
}

🔎 Implementation

Rule source
Test source

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