diff --git a/solution/1300-1399/1370.Increasing Decreasing String/README.md b/solution/1300-1399/1370.Increasing Decreasing String/README.md
index d341476b25a94..17579b3f9e369 100644
--- a/solution/1300-1399/1370.Increasing Decreasing String/README.md	
+++ b/solution/1300-1399/1370.Increasing Decreasing String/README.md	
@@ -184,6 +184,39 @@ func sortString(s string) string {
 }
 ```
 
+### **Javascript**
+
+```js
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var sortString = function (s) {
+    let rs = '';
+    const m = new Map();
+    for (let i = 0; i < s.length; i++) {
+        m.set(s[i], (m.get(s[i]) || 0) + 1);
+    }
+    const keys = [...m.keys()];
+    keys.sort();
+    while (rs.length < s.length) {
+        for (let j = 0; j < keys.length; j++) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+        for (let j = keys.length - 1; j >= 0; j--) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+    }
+    return rs;
+};
+```
+
 ### **...**
 
 ```
diff --git a/solution/1300-1399/1370.Increasing Decreasing String/README_EN.md b/solution/1300-1399/1370.Increasing Decreasing String/README_EN.md
index 504c74a2066f7..4134c4b1b2205 100644
--- a/solution/1300-1399/1370.Increasing Decreasing String/README_EN.md	
+++ b/solution/1300-1399/1370.Increasing Decreasing String/README_EN.md	
@@ -158,6 +158,39 @@ func sortString(s string) string {
 }
 ```
 
+### **Javascript**
+
+```js
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var sortString = function (s) {
+    let rs = '';
+    const m = new Map();
+    for (let i = 0; i < s.length; i++) {
+        m.set(s[i], (m.get(s[i]) || 0) + 1);
+    }
+    const keys = [...m.keys()];
+    keys.sort();
+    while (rs.length < s.length) {
+        for (let j = 0; j < keys.length; j++) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+        for (let j = keys.length - 1; j >= 0; j--) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+    }
+    return rs;
+};
+```
+
 ### **...**
 
 ```
diff --git a/solution/1300-1399/1370.Increasing Decreasing String/Solution.js b/solution/1300-1399/1370.Increasing Decreasing String/Solution.js
new file mode 100644
index 0000000000000..46b50ac40839d
--- /dev/null
+++ b/solution/1300-1399/1370.Increasing Decreasing String/Solution.js	
@@ -0,0 +1,28 @@
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var sortString = function (s) {
+    let rs = '';
+    const m = new Map();
+    for (let i = 0; i < s.length; i++) {
+        m.set(s[i], (m.get(s[i]) || 0) + 1);
+    }
+    const keys = [...m.keys()];
+    keys.sort();
+    while (rs.length < s.length) {
+        for (let j = 0; j < keys.length; j++) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+        for (let j = keys.length - 1; j >= 0; j--) {
+            if (m.get(keys[j]) != 0) {
+                rs += keys[j];
+                m.set(keys[j], m.get(keys[j]) - 1);
+            }
+        }
+    }
+    return rs;
+};