diff --git a/problems/0684.冗余连接.md b/problems/0684.冗余连接.md
index bfbdeba9..654ef469 100644
--- a/problems/0684.冗余连接.md
+++ b/problems/0684.冗余连接.md
@@ -303,6 +303,43 @@ func findRedundantConnection(edges [][]int) []int {
 ## JavaScript
 
 ```js
+const n = 1005;
+const father = new Array(n);
+// 并查集里寻根的过程
+const find = u => {
+    return u == father[u] ? u : father[u] = find(father[u]);
+};
+
+// 将v->u 这条边加入并查集
+const join = (u, v) => {
+    u = find(u);
+    v = find(v);
+    if(u == v) return;
+    father[v] = u;
+};
+
+// 判断 u 和 v是否找到同一个根，本题用不上
+const same = (u, v) => {
+    u = find(u);
+    v = find(v);
+    return u == v;
+};
+
+/**
+ * @param {number[][]} edges
+ * @return {number[]}
+ */
+var findRedundantConnection = function(edges) {
+    // 并查集初始化
+    for(let i = 0; i < n; i++){
+        father[i] = i;
+    }
+    for(let i = 0; i < edges.length; i++){
+        if(same(edges[i][0], edges[i][1])) return edges[i];
+        else join(edges[i][0], edges[i][1]);
+    }
+    return null;
+};
 ```
 
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