Check the array has empty element or not

Question

How can I check the array has empty element or not? Imagine this array,

var arr = [ 'a', 'b', , 'd'];

the arr[2] is undefined. I want to check this. If the element has empty element, return 'true' or return false. Maybe like this,

function hasEmptyElement(array){
    for (var i=0; i<array.length; i++){
        if (typeof arr[i] == 'undefined'){
          return true; 
          // and then ?
          // should I use double for loop or helper variable?
        }
    }
}

I confuse how can I do this. Please help me the clevers.

Answer 1

As of ES2016, you should use Array.prototype.includes:

const array = ["a", "b", , "d"];
array.includes(undefined); // true

(You don't need to write undefined, but this makes it more clear what's happening.)

Note that this method treats slots valued undefined and empty slots the same, although they're not. If you need to differentiate these two cases as well, starting from ES2017, you can use Object.values making the following expression true if there are empty slots in the array:

Object.values(array).length !== array.length; // true

Answer 2

First, note the difference between empty slots and slots with undefined value:

var arr = [/*empty slot*/, undefined];
Object.keys(arr); // ["1"] but not "0"
"0" in arr; // false
"1" in arr; // true

ES5 array methods skip empty slots. ES6 [].includes does not.

That means you can use

arr.includes(undefined); // has empty slot OR contains undefined value
arr.indexOf(undefined) > -1; // contains undefined value

If you want to test only if there are empty slots, you can iterate manually with a for loop and check whether all indices between 0 and the length of the array are present, e.g. with in operator.

(function() {
  for(var i=0; i<arr.length; ++i) if(!(i in arr)) return true;
  return false;
})(); // has empty slot

Or you can also use ES5 array methods and check if they skipped an index.

var n = 0;
arr.some((_,i) => i !== n++); // has empty slot

Answer 3

You could also use Array.prototype.findIndex()

var arr = ['a', 'b', , 'd'];

document.write(arr.findIndex(e => e === undefined) > -1);

Answer 4

try

var hasAnyEmptyElement = arr.filter(function(val){ return (typeof val) != "undefined" }).length != arr.length;

DEMO

var arr = [1,2];
arr[4] = 2;

var hasAnyEmptyElement = arr.filter(function(val){ return (typeof val) != "undefined" }).length != arr.length;

alert(hasAnyEmptyElement);

Answer 5

You can do something like that:

function hasEmptyElement(array){
    for (var i=0; i<array.length; i++){
        if (!(i in array)) {
            return true;
        }
    }
    return false;
}

The main point of this implementation is that it makes difference between [1,,3] and [1, undefined, 3]

Answer 6

var temp = arr.filter(item => item);

This will give you a new array with below elements: ["a", "b", "d"]

The above solution will help to remove empty as well as null values.

Answer 7

Simple implementation using set

var arr = [ 'a', 'b', , 'd'];
// Using Set from es6
var arraySet = new Set(arr)
arraySet.has(undefined) // returns true

Thanks!

Answer 8

You can try like this:

var arr = [ 'a', 'b',, 'd'];
function myfunc(arr) {
  for(var i=0; i<arr.length; i++) {
    if (!(i in arr)) return false;
  }
  return true;
}
alert( myfunc(arr));

Answer 9

For ES5- you can do

var arr = [ 'a', 'b', , 'd'];
arr.filter(function() { return true }).length === arr.length

That is going to return false if there is a undefined

ES2015 check includes

Answer 10

`Check null/undefined values in Array`

function checkNullValue(a) {
                    if (typeof (a) == 'undefined' || a === null) {
                        return false;
                    } else {
                        return true;
                    }

     }

    var arrayMonthVal = ['1','2',,'6','null', '8'];

    var pass = arrayMonthVal.some(checkNullValue);

Answer 11

I recently needed to know if a given array element was empty and this page helped me derive the following solution:

/** Determine if an array element is empty.
 *  @param {*[]} arr
 *  @param {number} [i] If not provided, check entire arr for empty.
 *  @return {boolean}
 */
const hasEmpty = (arr, i) => 0<=i 
  ? !arr.some((_, j) => j==i) 
  : Object.values(arr).length!==arr.length;

Answer 12

Making it simple you can use the below comparison for achieving the same.

function hasEmptyElement(array){
   for(var i=0;i<array.length;i++){
       if(my_arr[i] === "")   
          return false;
   }
   return true;
}

Answer 13

hello try this....

 if (typeof arr[i] == 'NULL'){
      return true; 
}

hope this may work