Update readme.md

Author: JSsnippets

README.md

@@ -1,14 +1,17 @@
 # JavaScript-snippets
 JavaScript Snippets
 
+
+# How to generate a random number in a given range
+
 ```javascript
-// Returns a random number between min (inclusive) and max (exclusive)
+// Returns a random number(float) between min (inclusive) and max (exclusive) 
 
 const getRandomNumber = (min, max) => Math.random() * (max - min) + min;
 
 getRandomNumber(2, 10)
 
- // Returns a random number between min (inclusive) and max (inclusive)
+ // Returns a random number(int) between min (inclusive) and max (inclusive)
 
 const getRandomNumberInclusive =(min, max)=> {
     min = Math.ceil(min);
@@ -18,3 +21,43 @@ const getRandomNumberInclusive =(min, max)=> {
 
 getRandomNumberInclusive(2, 10);
 ```
+
+# How to find the difference between two arrays.
+
+
+```javascript
+const firstArr = [5, 2, 1];
+const secondArr = [1, 2, 3, 4, 5];
+
+const diff = [
+    ...secondArr.filter(x => !firstArr.includes(x)),					
+    ...firstArr.filter(x => !secondArr.includes(x))
+];
+console.log('diff',diff) //[3,4]
+
+
+function arrayDiff(a, b) {
+    return [
+        ...a.filter(x => b.indexOf(x) === -1),
+        ...b.filter(x => a.indexOf(x) === -1)
+    ]
+}
+console.log('arrayDiff',arrayDiff(firstArr, secondArr)) //[3,4]
+
+
+
+
+const difference = (a, b) => {
+    const setA = new Set(a);
+    const setB = new Set(b);
+
+    return [
+        ...a.filter(x => !setB.has(x)),
+        ...b.filter(x => !setA.has(x))
+
+    ]
+};
+
+difference(firstArr, secondArr); //[3,4]
+console.log('difference',difference(firstArr, secondArr))
+```