What is the best procedure to check an array is empty or not in jQuery?

Question

I am using like to check if array is not empty

if(array != null){
  //code 
}

I also found like that

if(Array.isArray(array)){
//code
}

and

if(array.length){
//code
}

Which one is better to use above three ?

I would say `array.length === 0` or `typeof image_array !== 'undefined' && image_array.length > 0` but that is just me — Carsten Løvbo Andersen, May 31 '17 at 06:45
Here I do not want to check array is empty or not . I want to know which is better. @Robert,@Milan — Mohibul Hasan Rana, May 31 '17 at 06:53
please add what array could be, before checking. the second does only check if `array` is an array and not if there a any items in the array. — Nina Scholz, May 31 '17 at 06:56

Nina Scholz · Answer 1 · 2017-11-26T16:56:50.553

I suggest to use Array.isArray and the length property of the array

if (Array.isArray(array) && array.length) {
    // code
}

because it checks if array is an array and if the length has a truthy value.

Comparing your attempts:

Truthy check
```
if (array != null) { // which is basically the same as if (array) {
    //code 
}
```
This is true for all truthy values, like 1, 'a', {}. This result is not wanted.
Array check
```
if (Array.isArray(array)) {
    // code
}
```
This checks only if array is an array, but not the length of it. Empty arrays returns true, which is not wanted.
Length check
```
if (array.length) {
    // code
}
```
This works only for objects which may have a property of length, which have a truthy value.

While this comes close to the wanted result, it might be wrong, for example with objects like
```
{ length: 'foo' }
```
or with array-like objects.

score 7 · Answer 2 · answered May 31 '17 at 06:47

7

If you want to know if an Object is an Array, then Array.isArray() will do.

If you want to know if an Array has items, than array.length !== 0 will do.

If you want to know if a variable is not null than array !== null will do.

answered May 31 '17 at 06:47

philipp

15,947
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since the length can never be less than 0, you can just write if(array.length) - you don't need to compare against 0 – Andy Apr 21 '21 at 07:41

score 2 · Answer 3 · answered May 31 '17 at 06:47

2

I am use to array.length To check if array is not empty, use if( array.length > 0) {}

answered May 31 '17 at 06:47

gabriel

118
9

score 2 · Answer 4 · edited Jun 24 '18 at 19:33

2

It's better to check the length of the array but there is one issue in it. Consider if someone entered an undefined value in the array then the array will be empty but still have the length greater than 0.

for(var i=0,i<array.length;i++){
 if(typeof(array[i]) !== 'undefined'){

 };
};

edited Jun 24 '18 at 19:33

Rap

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answered May 31 '17 at 07:12

Deep Mistry

170
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14

1

That helped me as well! – Aashish May 31 '17 at 07:14

score 1 · Answer 5 · answered May 31 '17 at 06:50

var isEmptyArray = function(arr) {
    return (arr || []).length === 0;
}

var arr1 = [1, 2, 3];
var arr2 = [];
var arr3 = undefined;

console.log(isEmptyArray(arr1));  // false
console.log(isEmptyArray(arr2));  // true
console.log(isEmptyArray(arr3));  // true

score 1 · Answer 6 · answered May 31 '17 at 06:56

the best solution is

if (array.length>0){
....
}

but this sentence have a problem if you plan in deleting indexes from the array, since you can have an array like this [undefined,undefined,undefined], whos length is 3 but is technically empty.

var a = [1,2,3];
delete a[0];
delete a[1];
delete a[2];
a.length > 0 /// true
a /// [undefined x 3]

Take this in consideration to make the exact sentence

What is the best procedure to check an array is empty or not in jQuery?

6 Answers6