add js solution for combinationSum4

Author: jackeyjia

problems/0377.组合总和Ⅳ.md

@@ -201,6 +201,25 @@ func combinationSum4(nums []int, target int) int {
 }
 ```
 
+Javascript：
+```javascript
+const combinationSum4 = (nums, target) => {
+
+    let dp = Array(target + 1).fill(0);
+    dp[0] = 1;
+
+    for(let i = 0; i <= target; i++) {
+        for(let j = 0; j < nums.length; j++) {
+            if (i >= nums[j]) {
+                dp[i] += dp[i - nums[j]];
+            }
+        }
+    }
+
+    return dp[target];
+};
+```
+
 
 
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