Chore: Remove lodash

bin/eslint.js

@@ -66,11 +66,8 @@ function readStdin() {
  */
 function getErrorMessage(error) {
 
-    // Lazy loading because those are used only if error happened.
-    const fs = require("fs");
-    const path = require("path");
+    // Lazy loading because this is used only if an error happened.
     const util = require("util");
-    const lodash = require("lodash");
 
     // Foolproof -- thirdparty module might throw non-object.
     if (typeof error !== "object" || error === null) {
@@ -80,14 +77,7 @@ function getErrorMessage(error) {
     // Use templates if `error.messageTemplate` is present.
     if (typeof error.messageTemplate === "string") {
         try {
-            const templateFilePath = path.resolve(
-                __dirname,
-                `../messages/${error.messageTemplate}.txt`
-            );
-
-            // Use sync API because Node.js should exit at this tick.
-            const templateText = fs.readFileSync(templateFilePath, "utf-8");
-            const template = lodash.template(templateText);
+            const template = require(`../messages/${error.messageTemplate}.js`);
 
             return template(error.messageData || {});
         } catch {

docs/developer-guide/code-path-analysis.md

@@ -195,8 +195,6 @@ bar();
 ### To check whether or not this is reachable
 
 ```js
-var last = require("lodash").last;
-
 function isReachable(segment) {
     return segment.reachable;
 }
@@ -215,7 +213,7 @@ module.exports = function(context) {
 
         // Checks reachable or not.
         "ExpressionStatement": function(node) {
-            var codePath = last(codePathStack);
+            var codePath = codePathStack[codePathStack.length - 1];
 
             // Checks the current code path segments.
             if (!codePath.currentSegments.some(isReachable)) {
@@ -239,8 +237,6 @@ So a rule must not modify those instances.
 Please use a map of information instead.
 
 ```js
-var last = require("lodash").last;
-
 function hasCb(node, context) {
     if (node.type.indexOf("Function") !== -1) {
         return context.getDeclaredVariables(node).some(function(v) {
@@ -285,8 +281,10 @@ module.exports = function(context) {
 
         // Manages state of code paths.
         "onCodePathSegmentStart": function(segment) {
+            var funcInfo = funcInfoStack[funcInfoStack.length - 1];
+
             // Ignores if `cb` doesn't exist.
-            if (!last(funcInfoStack).hasCb) {
+            if (!funcInfo.hasCb) {
                 return;
             }
 
@@ -304,7 +302,7 @@ module.exports = function(context) {
 
         // Checks reachable or not.
         "CallExpression": function(node) {
-            var funcInfo = last(funcInfoStack);
+            var funcInfo = funcInfoStack[funcInfoStack.length - 1];
 
             // Ignores if `cb` doesn't exist.
             if (!funcInfo.hasCb) {

docs/developer-guide/code-path-analysis/README.md

@@ -195,8 +195,6 @@ bar();
 ### To check whether or not this is reachable
 
 ```js
-var last = require("lodash").last;
-
 function isReachable(segment) {
     return segment.reachable;
 }
@@ -215,7 +213,7 @@ module.exports = function(context) {
 
         // Checks reachable or not.
         "ExpressionStatement": function(node) {
-            var codePath = last(codePathStack);
+            var codePath = codePathStack[codePathStack.length - 1];
 
             // Checks the current code path segments.
             if (!codePath.currentSegments.some(isReachable)) {
@@ -239,8 +237,6 @@ So a rule must not modify those instances.
 Please use a map of information instead.
 
 ```js
-var last = require("lodash").last;
-
 function hasCb(node, context) {
     if (node.type.indexOf("Function") !== -1) {
         return context.getDeclaredVariables(node).some(function(v) {
@@ -285,8 +281,10 @@ module.exports = function(context) {
 
         // Manages state of code paths.
         "onCodePathSegmentStart": function(segment) {
+            var funcInfo = funcInfoStack[funcInfoStack - 1];
+
             // Ignores if `cb` doesn't exist.
-            if (!last(funcInfoStack).hasCb) {
+            if (!funcInfo.hasCb) {
                 return;
             }
 
@@ -304,7 +302,7 @@ module.exports = function(context) {
 
         // Checks reachable or not.
         "CallExpression": function(node) {
-            var funcInfo = last(funcInfoStack);
+            var funcInfo = funcInfoStack[funcInfoStack - 1];
 
             // Ignores if `cb` doesn't exist.
             if (!funcInfo.hasCb) {

lib/cli-engine/file-enumerator.js

@@ -38,7 +38,7 @@ const fs = require("fs");
 const path = require("path");
 const getGlobParent = require("glob-parent");
 const isGlob = require("is-glob");
-const { escapeRegExp } = require("lodash");
+const escapeRegExp = require("escape-string-regexp");
 const { Minimatch } = require("minimatch");
 
 const {

lib/cli-engine/formatters/html-template-message.js

@@ -0,0 +1,25 @@
+"use strict";
+
+module.exports = function(it, encodeHTML) {
+    const {
+        parentIndex,
+        lineNumber,
+        columnNumber,
+        severityNumber,
+        severityName,
+        message,
+        ruleUrl,
+        ruleId
+    } = it;
+
+    return `
+<tr style="display:none" class="f-${parentIndex}">
+    <td>${lineNumber}:${columnNumber}</td>
+    <td class="clr-${severityNumber}">${severityName}</td>
+    <td>${encodeHTML(message)}</td>
+    <td>
+        <a href="${ruleUrl}" target="_blank" rel="noopener noreferrer">${ruleId ? ruleId : ""}</a>
+    </td>
+</tr>
+`.trimLeft();
+};

lib/cli-engine/formatters/html-template-page.html → lib/cli-engine/formatters/html-template-page.js

@@ -1,3 +1,9 @@
+"use strict";
+
+module.exports = function(it) {
+    const { reportColor, reportSummary, date, results } = it;
+
+    return `
 <!DOCTYPE html>
 <html>
     <head>
@@ -88,15 +94,15 @@
         </style>
     </head>
     <body>
-        <div id="overview" class="bg-<%= reportColor %>">
+        <div id="overview" class="bg-${reportColor}">
             <h1>ESLint Report</h1>
             <div>
-                <span><%= reportSummary %></span> - Generated on <%= date %>
+                <span>${reportSummary}</span> - Generated on ${date}
             </div>
         </div>
         <table>
             <tbody>
-                <%= results %>
+                ${results}
             </tbody>
         </table>
         <script type="text/javascript">
@@ -113,3 +119,5 @@ <h1>ESLint Report</h1>
         </script>
     </body>
 </html>
+`.trimLeft();
+};

lib/cli-engine/formatters/html-template-result.js

@@ -0,0 +1,14 @@
+"use strict";
+
+module.exports = function(it, encodeHTML) {
+    const { color, index, filePath, summary } = it;
+
+    return `
+<tr class="bg-${color}" data-group="f-${index}">
+    <th colspan="4">
+        [+] ${encodeHTML(filePath)}
+        <span>${encodeHTML(summary)}</span>
+    </th>
+</tr>
+`.trimLeft();
+};

lib/cli-engine/formatters/html.js

@@ -4,17 +4,31 @@
  */
 "use strict";
 
-const lodash = require("lodash");
-const fs = require("fs");
-const path = require("path");
-
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
 
-const pageTemplate = lodash.template(fs.readFileSync(path.join(__dirname, "html-template-page.html"), "utf-8"));
-const messageTemplate = lodash.template(fs.readFileSync(path.join(__dirname, "html-template-message.html"), "utf-8"));
-const resultTemplate = lodash.template(fs.readFileSync(path.join(__dirname, "html-template-result.html"), "utf-8"));
+const encodeHTML = (function() {
+    const encodeHTMLRules = {
+        "&": "&",
+        "<": "&#60;",
+        ">": "&#62;",
+        '"': "&#34;",
+        "'": "&#39;",
+        "/": "&#47;"
+    };
+    const matchHTML = /[&<>"'/]/ug;
+
+    return function(code) {
+        return code
+            ? code.toString().replace(matchHTML, m => encodeHTMLRules[m] || m)
+            : "";
+    };
+}());
+
+const pageTemplate = require("./html-template-page.js");
+const messageTemplate = require("./html-template-message.js");
+const resultTemplate = require("./html-template-result.js");
 
 /**
  * Given a word and a count, append an s if count is not one.
@@ -80,7 +94,9 @@ function renderMessages(messages, parentIndex, rulesMeta) {
         if (rulesMeta) {
             const meta = rulesMeta[message.ruleId];
 
-            ruleUrl = lodash.get(meta, "docs.url", null);
+            if (meta && meta.docs && meta.docs.url) {
+                ruleUrl = meta.docs.url;
+            }
         }
 
         return messageTemplate({
@@ -92,7 +108,7 @@ function renderMessages(messages, parentIndex, rulesMeta) {
             message: message.message,
             ruleId: message.ruleId,
             ruleUrl
-        });
+        }, encodeHTML);
     }).join("\n");
 }
 
@@ -108,8 +124,7 @@ function renderResults(results, rulesMeta) {
         color: renderColor(result.errorCount, result.warningCount),
         filePath: result.filePath,
         summary: renderSummary(result.errorCount, result.warningCount)
-
-    }) + renderMessages(result.messages, index, rulesMeta)).join("\n");
+    }, encodeHTML) + renderMessages(result.messages, index, rulesMeta)).join("\n");
 }
 
 //------------------------------------------------------------------------------

lib/init/autoconfig.js

@@ -9,7 +9,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-const lodash = require("lodash"),
+const equal = require("fast-deep-equal"),
     recConfig = require("../../conf/eslint-recommended"),
     ConfigOps = require("@eslint/eslintrc/lib/shared/config-ops"),
     { Linter } = require("../linter"),
@@ -329,7 +329,7 @@ function extendFromRecommended(config) {
     const recRules = Object.keys(recConfig.rules).filter(ruleId => ConfigOps.isErrorSeverity(recConfig.rules[ruleId]));
 
     recRules.forEach(ruleId => {
-        if (lodash.isEqual(recConfig.rules[ruleId], newConfig.rules[ruleId])) {
+        if (equal(recConfig.rules[ruleId], newConfig.rules[ruleId])) {
             delete newConfig.rules[ruleId];
         }
     });

lib/linter/apply-disable-directives.js

@@ -5,8 +5,6 @@
 
 "use strict";
 
-const lodash = require("lodash");
-
 /**
  * Compares the locations of two objects in a source file
  * @param {{line: number, column: number}} itemA The first object
@@ -124,7 +122,21 @@ module.exports = ({ directives, problems, reportUnusedDisableDirectives = "off"
         .map(directive => Object.assign({}, directive, { unprocessedDirective: directive }))
         .sort(compareLocations);
 
-    const lineDirectives = lodash.flatMap(directives, directive => {
+    /**
+     * Returns a new array formed by applying a given callback function to each element of the array, and then flattening the result by one level.
+     * TODO(stephenwade): Replace this with array.flatMap when we drop support for Node v10
+     * @param {any[]} array The array to process
+     * @param {Function} fn The function to use
+     * @returns {any[]} The result array
+     */
+    function flatMap(array, fn) {
+        const mapped = array.map(fn);
+        const flattened = [].concat(...mapped);
+
+        return flattened;
+    }
+
+    const lineDirectives = flatMap(directives, directive => {
         switch (directive.type) {
             case "disable":
             case "enable":

lib/linter/linter.js

@@ -15,7 +15,7 @@ const
     eslintScope = require("eslint-scope"),
     evk = require("eslint-visitor-keys"),
     espree = require("espree"),
-    lodash = require("lodash"),
+    extend = require("deep-extend"),
     BuiltInEnvironments = require("@eslint/eslintrc/conf/environments"),
     pkg = require("../../package.json"),
     astUtils = require("../shared/ast-utils"),
@@ -529,8 +529,8 @@ function normalizeVerifyOptions(providedOptions, config) {
 function resolveParserOptions(parserName, providedOptions, enabledEnvironments) {
     const parserOptionsFromEnv = enabledEnvironments
         .filter(env => env.parserOptions)
-        .reduce((parserOptions, env) => lodash.merge(parserOptions, env.parserOptions), {});
-    const mergedParserOptions = lodash.merge(parserOptionsFromEnv, providedOptions || {});
+        .reduce((parserOptions, env) => extend(parserOptions, env.parserOptions), {});
+    const mergedParserOptions = extend(parserOptionsFromEnv, providedOptions || {});
     const isModule = mergedParserOptions.sourceType === "module";
 
     if (isModule) {
@@ -1286,7 +1286,9 @@ class Linter {
         const filenameToExpose = normalizeFilename(filename);
         const text = ensureText(textOrSourceCode);
         const preprocess = options.preprocess || (rawText => [rawText]);
-        const postprocess = options.postprocess || lodash.flatten;
+
+        // TODO(stephenwade): Replace this with array.flat() when we drop support for Node v10
+        const postprocess = options.postprocess || (array => [].concat(...array));
         const filterCodeBlock =
             options.filterCodeBlock ||
             (blockFilename => blockFilename.endsWith(".js"));