Merge pull request #40 from gmihov001/patch-13

Explained filter method

Author: alesanchezr

exercises/12-Delete-element/README.md

@@ -1,16 +1,40 @@
 # `12` Delete element
 
-The only way to delete `Daniella` from the array (without cheating) will be to create a new list with all the other people but Daniella.
+One of the ways to delete Daniella from the array (without cheating) will be to create a new list with all the other people but Daniella. 
 
-## 📝Instructions:
+That happens to be the default behavior of the `Array.filter()` method which you should know. Similar to the `.forEach()` and `.map()` methods, it is a higher-order function, which means that it calls another function to achieve its goals. That secondary **callback** function is called by the `.filter()` with up to three parameters (optional) and the return can only be one thing - a condition:
+
+```js
+
+(elementBeingIterated, indexOfThatElement, theIteratedArray) => condition;
+
+```
+
+So if you want to keep only the numbers 2 and 4 from an array of numbers, your filter method would look like this:
+
+```js
+let array = [2, 9, 5, 6, 4, 1, 2, 3, 4];
+
+let newArray = array.filter((element) => element === 2 || element === 4);
+
+console.log(newArray); // outcome is [2, 4, 2, 4]
+
+```
+The `.filter()` method automatically creates a new array in which only the elements that pass the condition are kept. Any other elements are dropped from the newArray. 
+
+You can learn more about this method [here](https://www.w3schools.com/jsref/jsref_filter.asp)
+
+
+### Instructions:
+
+1. Please create a `deletePerson` function that deletes any given person from an array and returns a new array without that person.
 
-1. Please create a `deletePerson` function that deletes any given person from the array and returns a new array without that person.
 
 ### Expected result:
 
  ```js
 
- ['juan', 'ana', 'michelle', 'stefany', 'lucy', 'barak']
-['ana', 'michelle', 'daniella', 'stefany', 'lucy', 'barak']
+['juan', 'ana', 'michelle', 'stefany', 'lucy', 'barak', 'emilio']
+['ana', 'michelle', 'daniella', 'stefany', 'lucy', 'barak', 'emilio']
 ['juan', 'ana', 'michelle', 'daniella', 'stefany', 'lucy', 'barak']
-```
+```