+ /**
+ * Checks whether a given node is unused expression or not.
+ * @param {ASTNode} node The node itself
+ * @returns {boolean} The node is an unused expression.
+ * @private
+ */
+ function isUnusedExpression(node) {
+ const parent = node.parent;
+
+ if (parent.type === "ExpressionStatement") {
+ return true;
+ }
+
+ if (parent.type === "SequenceExpression") {
+ const isLastExpression = parent.expressions[parent.expressions.length - 1] === node;
+
+ if (!isLastExpression) {
+ return true;
+ }
+ return isUnusedExpression(parent);
+ }
+
+ return false;
+ }
+