Learn this before React
<p>In this tutorial we will explore top fundamental JavaScript concepts necessary to know in order to have an effective React Js/React Native learning.</p>
<h1>Table of contents</h1>
<p>1.maps() and filters()</p>
<p>2.slice() and splice()</p>
<p>3.find() and findIndex()</p>
<p>4.destructuring()</p>
<p>5.rest and spread operators</p>
<p>6.promise</p>
<h1>1.map</h1>
<ul>
<li>The arr.map method is one of the most useful and often used.</li>
<li>It calls the function for each element of the array and returns the array of results.</li>
</ul>
<p>The syntax is :</p>
<pre>
let result = arr.map(function(item, index, array) {
});
</pre>
<h1>filter</h1>
<ul>
<li>The find method looks for a single (first) element that makes the function return true.</li>
<li>If there may be many, we can use arr.filter(fn).</li>
</ul>
<p>The syntax is similar to find, but filter returns an array of all matching elements</p>
<p><a href="https://medium.com/@vishalkrishna8/learn-this-before-react-430a4c722620">Read More</a></p>