From 01e4ae68b3c05727ee3ae9abe832ebfb159a2a97 Mon Sep 17 00:00:00 2001
From: irwanphan <irwanphan@gmail.com>
Date: Sat, 24 Oct 2020 17:29:26 +0700
Subject: [PATCH] check if the new one and the last one are operators, if they
 are, then remove last one

---
 script.js | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/script.js b/script.js
index 4a47262..a4c58af 100644
--- a/script.js
+++ b/script.js
@@ -30,7 +30,21 @@ const displayHandler = () => {
 };
 
 const appendText = (character) => {
-  operationString.innerHTML += character
+  checkRemoveOperator(operationString, character);
+  operationString.innerHTML += character;
+}
+
+function checkRemoveOperator(str, newChar) {
+  let operators = ["-", "+", "/", "*"];
+  let isOperator = false; //check is the last one is an operator
+  let isAnotherOperator = false; //check if the new one is an operator
+  for (const operator of operators){
+    if(str.innerHTML.slice(-1) == operator) isOperator = true;
+  }
+  for (const operator of operators){
+    if(newChar == operator) isAnotherOperator = true;
+  }
+  if (isOperator && isAnotherOperator) removeLastChar(); //if the new one and the last one are operators, remove last one
 }
 
 const removeLastChar = () => {