In this tutorial we will explore top fundamental JavaScript concepts necessary to know in order to have an effective React Js/React Native learning.
Table of contents
1.maps() and filters()
2.slice() and splice()
3.find() and findIndex()
4.destructuring()
5.rest and spread operators
6.promise
1.map
- The arr.map method is one of the most useful and often used.
- It calls the function for each element of the array and returns the array of results.
The syntax is :
let result = arr.map(function(item, index, array) {
});
filter
- The find method looks for a single (first) element that makes the function return true.
- If there may be many, we can use arr.filter(fn).
The syntax is similar to find, but filter returns an array of all matching elements