diff --git a/80_remove_duplicates.js b/80_remove_duplicates.js
new file mode 100644
index 0000000..ce2932f
--- /dev/null
+++ b/80_remove_duplicates.js
@@ -0,0 +1,39 @@
+const testProblems = [{
+  input: [1, 1, 1],
+  output: [1, 1]
+}, {
+  input: [1, 1, 1, 2, 2, 2, 3],
+  output: [1, 1, 2, 2, 3]
+}, {
+  input: [1, 2, 3, 4, 5, 6, 7],
+  output: [1, 2, 3, 4, 5, 6, 7]
+}, {
+  input: [1, 1, 1, 1],
+  output: [1, 1]
+}, {
+  input: [1, 1, 1, 1, 2],
+  output: [1, 1, 2]
+}]
+
+var removeDuplicates = function(nums) {
+  var indexsToBeRemoved = []
+  var deleteMode = false
+  var alreadyDelete = 0
+  nums.reduce((prev, cur, curIdx) => {
+    if (prev === cur && deleteMode) {
+      indexsToBeRemoved.push(curIdx)
+    } else if (prev === cur) {
+      deleteMode = true
+    } else {
+      deleteMode = false
+    }
+    return cur
+  }, 'x')
+  indexsToBeRemoved.map((idx, shift) => nums.splice(idx - shift, 1))
+  return nums.length
+};
+
+testProblems.map(problem => {
+  var answer = removeDuplicates(problem.input)
+  console.log(`Answer: ${JSON.stringify(answer)} | Expected: ${JSON.stringify(problem.output)}`)
+})