some fixes

front/src/components/Main.jsx

@@ -3,58 +3,50 @@ import { useState, useEffect } from 'react';
 import DataService from '../services/DataService';
 
 export default function Main(props) {
-    function getRandomNumber() {
+    const url = 'http://localhost:8080';
+    const urlRandomNumber = '/getRandomNumber';
+    const urlCalc = '/sum?val1=num1&val2=num2';
+    const urlLength = '/length?name=strName';
+    const urlUpperCase = '/upperCase?word=strWord';
+    
+    function get(url2) {
         fetch(
-            'http://localhost:8080/getRandomNumber',
+            url + url2,
             {
               method: 'GET',
               headers: { 'Content-Type': 'application/json' },            
             }
           ).then(resp => resp.text()).then(alert);
     }
+
+    function getRandomNumber() {
+        get(urlRandomNumber);
+     
+    }
     function req_calc() {
-        console.log(num1);
-        fetch(
-            `http://localhost:8080/sum?val1=${num1}&val2=${num2}`,
-            {
-              method: 'GET',
-              headers: { 'Content-Type': 'application/json' },            
-            }
-          ).then(resp => resp.text()).then(alert);
+        get(urlCalc.replace("num1", num1).replace("num2", num2));    
     }
     const [num1, setnum1] = useState('');
     const [num2, setnum2] = useState('');
     function valueChanged1(event) {
+        console.log(event.target);
         setnum1(event.target.value);
     }
     function valueChanged2(event) {
         setnum2(event.target.value);
     }
     function req_length() {
-        console.log(num1);
-        fetch(
-            `http://localhost:8080/length?name=${name}`,
-            {
-              method: 'GET',
-              headers: { 'Content-Type': 'application/json' },            
-            }
-          ).then(resp => resp.text()).then(alert);
+        get(urlLength.replace("strName", strName));
+    
     }
-    const [name, setName] = useState('');
+    const [strName, setName] = useState('');
     function valueChangedName(event) {
         setName(event.target.value);
     }
     function req_upperCase() {
-        console.log(num1);
-        fetch(
-            `http://localhost:8080/upperCase?word=${word}`,
-            {
-              method: 'GET',
-              headers: { 'Content-Type': 'application/json' },            
-            }
-          ).then(resp => resp.text()).then(alert);
+        get(urlUpperCase.replace("strWord", strWord));
     }
-    const [word, setWord] = useState('');
+    const [strWord, setWord] = useState('');
     function valueChangedWord(event) {
         setWord(event.target.value);
     }