array.flatmap() method in JavaScript.

The JavaScript array.flatMap() function flattens the given nested array into a new flat array.

Following is the code for the array.flatMap() method −


 Live Demo

<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   .sample {
      font-size: 20px;
      font-weight: 500;
<h1>JavaScript Array flatMap()</h1>
<div class="sample"></div>
<button class="Btn">CLICK HERE</button>
Click on the above button to convert the nested array to flat array
   let fillEle = document.querySelector(".sample");
   let arr = ["cow", ["bull", "lion", "tiger"], "sheep"];
   for (x of arr.entries()) {
      fillEle.innerHTML += x + "<br>";
   var entries = arr.entries();
   document.querySelector(".Btn").addEventListener("click", () => {
      arr = arr.flatMap((x) => x);
      fillEle.innerHTML = "";
      for (x of arr.entries()) {
         fillEle.innerHTML += x + "<br>";


The above code will produce the following output −

On clicking the “CLICK HERE” button −

Updated on: 16-Jul-2020


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