added simple Username change website

js/changeUsername.js

@@ -0,0 +1,25 @@
+async function setUser() {
+  let user = await (await fetch("/api/getuser")).json()
+  //user["username"],user["error"]
+  if(user["username"])document.getElementById("username").innerText = `Current User: ${user["username"]}`
+  if(user["error"])document.getElementById("username").innerText = `Error: ${user["error"]}`
+
+}
+
+setUser()
+
+async function change(){
+  if(window.confirm("Are you sure that you want to change your Username?")){
+    let re = await (await post("/api/changeUsername",{"currentPW":document.getElementById("currentPW").value.toString(),"newUsername":document.getElementById("newUsername").value})).json()
+    document.getElementById("response").innerText = re["error"] || re["success"]
+    document.getElementById("response").style="color:green"
+    if(re["error"]) {
+      document.getElementById("response").style="color:red"
+    }
+    document.getElementById("currentPW").value = ""
+    document.getElementById("newUsername").value = ""
+    setUser()
+  }
+}
+
+document.getElementById("submit").addEventListener("click",change)