JavaScript - convert array with null value to string

We have an array that contains some string values as well as some nullish values.

We are required to write a JavaScript function that takes in this array and returns a string constructed by joining values of the array and omitting nullish values.

Following is our array, with some null and undefined values −

const arr = ["Here", "is", null, "an", undefined, "example", 0, "", "of", "a", null, "sentence"];

Let’s write the code for this function −


const arr = ["Here", "is", null, "an", undefined, "example", 0, "", "of",
"a", null, "sentence"];
const joinArray = arr => {
   const sentence = arr.reduce((acc, val) => {
      return acc + (val || "");
   }, "");
   return sentence;


Following is the output in the console −