save previous value

js/main.js

@@ -1,5 +1,31 @@
 if (window.wlb === undefined) {
-  window.wlb = {
+  const SaveInput = function () {
+    this.timeInput = null;
+    this.lsKey = "input";
+  };
+  SaveInput.prototype.init = function () {
+    this.timeInput = document.getElementById("time-input");
+    this.ls = window.localStorage;
+    if (this.ls) {
+      this.timeInput.value = this.ls.getItem(this.lsKey);
+      this.bindAll();
+    }
+  };
+  SaveInput.prototype.bindAll = function () {
+    this.timeInput.addEventListener("input", this.onValueChange.bind(this));
+    this.timeInput.addEventListener("change", this.onValueChange.bind(this));
+  };
+  SaveInput.prototype.onValueChange = function () {
+    const currentValue = this.timeInput.value;
+    this.ls.setItem(this.lsKey, currentValue);
+  };
 
+  window.wlb = {
+    init: function () {
+      this.saveInput.init();
+    },
+    saveInput: new SaveInput(),
   };
+
+  window.wlb.init();
 }