Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/NoUnusedVariablesRule.mjs

@@ -0,0 +1,50 @@
+import { GraphQLError } from '../../error/GraphQLError.mjs';
+
+/**
+ * No unused variables
+ *
+ * A GraphQL operation is only valid if all variables defined by an operation
+ * are used, either directly or within a spread fragment.
+ *
+ * See https://spec.graphql.org/draft/#sec-All-Variables-Used
+ */
+export function NoUnusedVariablesRule(context) {
+  let variableDefs = [];
+  return {
+    OperationDefinition: {
+      enter() {
+        variableDefs = [];
+      },
+
+      leave(operation) {
+        const variableNameUsed = Object.create(null);
+        const usages = context.getRecursiveVariableUsages(operation);
+
+        for (const { node } of usages) {
+          variableNameUsed[node.name.value] = true;
+        }
+
+        for (const variableDef of variableDefs) {
+          const variableName = variableDef.variable.name.value;
+
+          if (variableNameUsed[variableName] !== true) {
+            context.reportError(
+              new GraphQLError(
+                operation.name
+                  ? `Variable "$${variableName}" is never used in operation "${operation.name.value}".`
+                  : `Variable "$${variableName}" is never used.`,
+                {
+                  nodes: variableDef,
+                },
+              ),
+            );
+          }
+        }
+      },
+    },
+
+    VariableDefinition(def) {
+      variableDefs.push(def);
+    },
+  };
+}