diff --git a/01/app.js b/01/app.js
index e69de29..59335cf 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,9 @@
+function showTime() {
+    console.log('showTime');
+
+    const time = (new Date()).toLocaleTimeString();
+    console.log(time);
+}
+
+showTime();
+
diff --git a/02/app.js b/02/app.js
index e69de29..cfba209 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,5 @@
+function sayHello(name){
+console.log('Cześć ' + name + '!')
+}
+
+sayHello('devmentor.pl')
\ No newline at end of file
diff --git a/03/app.js b/03/app.js
index e69de29..247a598 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,16 @@
+const getSum = function(limit) {
+    console.log(limit);
+
+    let result = 0;
+    for(let i=1; i<=limit; i++) {
+        result = result + i;
+    }
+
+    return result;
+}
+
+const res1 = getSum(4);
+console.log(res1);
+
+const res2 = getSum(5);
+console.log(res2);
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index e69de29..83f1d2d 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,18 @@
+function runTimer() {
+    console.log('start')
+
+    let iter = 0;
+    const idInterval = setInterval(function () {
+
+        const time = (new Date()).toLocaleTimeString();
+        console.log(time);
+
+        iter++;
+        console.log(iter);
+        
+        if (iter === 5) { clearInterval(idInterval); }
+
+    }, 1000);
+}
+
+runTimer()