How to Remove undefined Values From a JavaScript Array?

How to Remove undefined Values From a JavaScript Array?#

Removing undefined values from a JavaScript array can be easily achieved using various JavaScript methods.

Method 1: Using filter() method#

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

let arr = ["hello", undefined, "world", undefined, "javascript"];
arr = arr.filter(Boolean);
console.log(arr);
// Output: ["hello", "world", "javascript"]

Method 2: Using forEach() method#

The forEach() method executes a provided function once for each array element.

let arr = ["hello", undefined, "world", undefined, "javascript"];
let newArray = [];
arr.forEach(function(element) {
  if(element !== undefined) {
    newArray.push(element);
  }
});
console.log(newArray);
// Output: ["hello", "world", "javascript"]

Method 3: Using splice() method#

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

let arr = ["hello", undefined, "world", undefined, "javascript"];
for(let i = arr.length-1; i >= 0; i--){
  if(arr[i] === undefined){
    arr.splice(i,1);
  }
}
console.log(arr);
// Output: ["hello", "world", "javascript"]

Using any of these methods, we can easily remove undefined values from a JavaScript array.