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app_vue/node_modules/eslint/lib/rules/no-useless-call.js

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+/**
+ * @fileoverview A rule to disallow unnecessary `.call()` and `.apply()`.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Checks whether or not a node is a `.call()`/`.apply()`.
+ * @param {ASTNode} node A CallExpression node to check.
+ * @returns {boolean} Whether or not the node is a `.call()`/`.apply()`.
+ */
+function isCallOrNonVariadicApply(node) {
+    const callee = astUtils.skipChainExpression(node.callee);
+
+    return (
+        callee.type === "MemberExpression" &&
+        callee.property.type === "Identifier" &&
+        callee.computed === false &&
+        (
+            (callee.property.name === "call" && node.arguments.length >= 1) ||
+            (callee.property.name === "apply" && node.arguments.length === 2 && node.arguments[1].type === "ArrayExpression")
+        )
+    );
+}
+
+
+/**
+ * Checks whether or not `thisArg` is not changed by `.call()`/`.apply()`.
+ * @param {ASTNode|null} expectedThis The node that is the owner of the applied function.
+ * @param {ASTNode} thisArg The node that is given to the first argument of the `.call()`/`.apply()`.
+ * @param {SourceCode} sourceCode The ESLint source code object.
+ * @returns {boolean} Whether or not `thisArg` is not changed by `.call()`/`.apply()`.
+ */
+function isValidThisArg(expectedThis, thisArg, sourceCode) {
+    if (!expectedThis) {
+        return astUtils.isNullOrUndefined(thisArg);
+    }
+    return astUtils.equalTokens(expectedThis, thisArg, sourceCode);
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "disallow unnecessary calls to `.call()` and `.apply()`",
+            category: "Best Practices",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/no-useless-call"
+        },
+
+        schema: [],
+
+        messages: {
+            unnecessaryCall: "Unnecessary '.{{name}}()'."
+        }
+    },
+
+    create(context) {
+        const sourceCode = context.getSourceCode();
+
+        return {
+            CallExpression(node) {
+                if (!isCallOrNonVariadicApply(node)) {
+                    return;
+                }
+
+                const callee = astUtils.skipChainExpression(node.callee);
+                const applied = astUtils.skipChainExpression(callee.object);
+                const expectedThis = (applied.type === "MemberExpression") ? applied.object : null;
+                const thisArg = node.arguments[0];
+
+                if (isValidThisArg(expectedThis, thisArg, sourceCode)) {
+                    context.report({ node, messageId: "unnecessaryCall", data: { name: callee.property.name } });
+                }
+            }
+        };
+    }
+};