diff --git a/modules/1_basics/index.js b/modules/1_basics/index.js
index cb5ff10..2bcd350 100644
--- a/modules/1_basics/index.js
+++ b/modules/1_basics/index.js
@@ -1,39 +1,138 @@
 /**
  * Change the capitalization of all letters in a string
  */
-export const changeCase = () => {};
+export const changeCase = (str) => {
+    let result = '';
+    for(let i = 0; i < str.length; i++) {
+        let char = str.charAt(i);
+        if(char === char.toUpperCase()){
+            char = char.toLowerCase();
+        }else if(char === char.toLowerCase()){
+            char = char.toUpperCase();
+        }
+        result = result + char;
+    }
+    return result;
+};
 
 /**
  * Filter out the non-unique values in an array
  */
-export const filterNonUnique = () => {};
+export const filterNonUnique = (arr) => {
+    let result = [];
+    for (const element of arr) {
+        let elmentCounter = 0;
+        for(const el2 of arr) {
+            if (element === el2){
+                elmentCounter++;
+            }
+        }
+        if(elmentCounter === 1) {
+        result.push(element);
+        }
+    }
+    return result;
+};
 
 /**
  * Sort string in alphabetical order
  */
-export const alphabetSort = () => {};
+export const alphabetSort = (str) => {
+    let chars = str.split('');
+    let sortedChars = chars.sort();
+    return sortedChars.join('');
+};
 
 /**
  * Get min integer
  */
-export const getSecondMinimum = () => {};
+export const getSecondMinimum = (arr) => {
+    let min = null;
+    let secMin = null;
+    arr = arr.sort();
+    for (const el of arr){
+        if (min === null || el <= min){
+            min = el;
+        } else if (secMin === null || el <= secMin) {
+            secMin = el;
+        }
+    }
+    return secMin != null ? secMin : min;
+};
 
 /**
  * Double every even integer
  */
-export const doubleEveryEven = () => {};
+export const doubleEveryEven = (arr) => {
+    let result = [];
+    for(const element of arr) {
+        if(element % 2 === 0){
+            result.push(element * 2);
+        }else{
+            result.push(element);
+        }
+    }
+    return result;
+};
 
 /**
  * Create array with all possible pairs of two arrays
  */
-export const getArrayElementsPairs = () => {};
+export const getArrayElementsPairs = (arr1, arr2) => {
+    let result = [];
+    for(const el1 of arr1){
+        for (const el2 of arr2){
+            result.push([el1, el2]);
+        }
+    }
+    return result;
+};
 
 /**
  * Deep equal
  */
-export const deepEqual = () => {};
+export const deepEqual = (o1, o2) => {
+    function isObject(obj) {
+        return obj === Object(obj);
+    }
+    
+    if (o1 === o2) {
+        return true;
+    }
+    
+    for(var p in o1){
+        if(!o2.hasOwnProperty(p)) { // o2 does not have such property
+            return false;
+        }
+        if(!isObject(o1[p]) && o1[p]!== o2[p]) { // is simple type and not equal to o2
+            return false;
+        } else if (isObject(o1[p]) && !isObject(o2[p])) { // o2 property is not complex type
+            return false;
+        } else if (isObject(o1[p]) && isObject(o2[p])){ // both are complex types
+            if(!deepEqual(o1[p], o2[p])) { // recursion check nested property
+                return false;
+            }
+        }
+    }
+    return true; // has not failed the previous steps
+};
 
 /**
  * Format date
  */
-export const formatDate = () => {};
+export const formatDate = (date) => {
+    if (Array.isArray(date)){
+        date = new Date(date[0], date[1], date[2]);
+    } else {
+        date = new Date(date);
+    }
+      
+    let day = date.getDate() + '';
+    day = day.padStart(2, '0');
+    let month = date.getMonth() + 1 + '';
+    month = month.padStart(2,'0');
+    let year = date.getFullYear() + '';
+    year = year.slice(-2);
+    let result = `${day}.${month}.${year}`;
+    return result;
+};