perf: optimize duplicate (#24)

* perf: optimize mark duplicate

* add

* add

* add

* add

* add

src/util.js

@@ -11,11 +11,25 @@ function dealInput (para) {
   return arr;
 };
 
-function matchKeyword(content, keywords) {
+function matchKeyword (content, keywords) {
   return keywords.find(item => content.toLowerCase().includes(item));
 };
 
+function testDuplicate(body) {
+  if (!body || !body.startsWith('Duplicate of')) {
+    return false
+  }
+
+  let arr = body.split(' ');
+  if (arr[0] == 'Duplicate' && arr[1] == 'of') {
+    return true;
+  } else {
+    return false;
+  }
+};
+
 module.exports = {
   dealInput,
   matchKeyword,
+  testDuplicate,
 };