tools: decrease code duplication for isString() in lint rules

This commit makes isString() a reusable utility
function for core's custom ESLint rules.

PR-URL: https://github.com/nodejs/node/pull/27719
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Masashi Hirano <shisama07@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

4 files changed, 7 insertions, 25 deletions

diff --git a/tools/eslint-rules/no-duplicate-requires.js b/tools/eslint-rules/no-duplicate-requires.js
index 05a379eba6..8c4b7a4c27 100644
--- a/tools/eslint-rules/no-duplicate-requires.js
+++ b/tools/eslint-rules/no-duplicate-requires.js
@@ -4,17 +4,13 @@
  */
 'use strict';
 
-const { isRequireCall } = require('./rules-utils.js');
+const { isRequireCall, isString } = require('./rules-utils.js');
 
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
 
 
-function isString(node) {
-  return node && node.type === 'Literal' && typeof node.value === 'string';
-}
-
 function isTopLevel(node) {
   do {
     if (node.type === 'FunctionDeclaration' ||
diff --git a/tools/eslint-rules/require-common-first.js b/tools/eslint-rules/require-common-first.js
index 2b04a98d9f..4096ee2771 100644
--- a/tools/eslint-rules/require-common-first.js
+++ b/tools/eslint-rules/require-common-first.js
@@ -4,7 +4,7 @@
 'use strict';
 
 const path = require('path');
-const { isRequireCall } = require('./rules-utils.js');
+const { isRequireCall, isString } = require('./rules-utils.js');
 
 //------------------------------------------------------------------------------
 // Rule Definition
@@ -16,15 +16,6 @@ module.exports = function(context) {
   const foundModules = [];
 
   /**
-   * Function to check if a node is a string literal.
-   * @param {ASTNode} node The node to check.
-   * @returns {boolean} If the node is a string literal.
-   */
-  function isString(node) {
-    return node && node.type === 'Literal' && typeof node.value === 'string';
-  }
-
-  /**
    * Function to check if the path is a module and return its name.
    * @param {String} str The path to check
    * @returns {String} module name
diff --git a/tools/eslint-rules/required-modules.js b/tools/eslint-rules/required-modules.js
index 40cb8e46e5..06c998c7f5 100644
--- a/tools/eslint-rules/required-modules.js
+++ b/tools/eslint-rules/required-modules.js
@@ -4,7 +4,7 @@
  */
 'use strict';
 
-const { isRequireCall } = require('./rules-utils.js');
+const { isRequireCall, isString } = require('./rules-utils.js');
 
 //------------------------------------------------------------------------------
 // Rule Definition
@@ -26,15 +26,6 @@ module.exports = function(context) {
   }
 
   /**
-   * Function to check if a node is a string literal.
-   * @param {ASTNode} node The node to check.
-   * @returns {boolean} If the node is a string literal.
-   */
-  function isString(node) {
-    return node && node.type === 'Literal' && typeof node.value === 'string';
-  }
-
-  /**
    * Function to check if the path is a required module and return its name.
    * @param {String} str The path to check
    * @returns {undefined|String} required module name or undefined
diff --git a/tools/eslint-rules/rules-utils.js b/tools/eslint-rules/rules-utils.js
index 713a49bf7a..462ab7c2ff 100644
--- a/tools/eslint-rules/rules-utils.js
+++ b/tools/eslint-rules/rules-utils.js
@@ -8,6 +8,10 @@ function isRequireCall(node) {
 }
 module.exports.isRequireCall = isRequireCall;
 
+module.exports.isString = function(node) {
+  return node && node.type === 'Literal' && typeof node.value === 'string';
+};
+
 module.exports.isDefiningError = function(node) {
   return node.expression &&
          node.expression.type === 'CallExpression' &&