Check if first item in array is empty value

Question

I have seen dozens of questions asked for checking if an array is empty. But I can't find the question on how to check if the first item in an array is empty.

Currently, I am doing this check on this way, but I highly doubt that it is the correct way to do this.

var specialtiesListArray = ['', 'not', 'empty', 'value'];

if (specialtiesListArray[0] == '') {
    
    specialtiesListArray.shift(); // <== Removing the first item when empty.

}

console.info({ specialtiesListArray });

The above works fine, but I am wondering is this ok? Are there better ways. And if someone knows a duplicate, then please let me know. I gladly delete the question if it has already been answered.

pd.isnull(x) or not bool(x) would be pretty good at finding empty values. — Zorgoth
– Zorgoth, Commented May 24, 2022 at 17:27
it's good. I don't see any problem with keeping this code as it is, it is simple and clear to understand — Mister Jojo
– Mister Jojo, Commented May 24, 2022 at 17:52
The code is fine as it is, there isn't any noticeable problem. My only piece of advice is to use === in place of ==, in this way if you have empty arrays or zeros it won't delete the element. Remember that in JS [] == '' or 0 == '' are true — Christian Vincenzo Traina
– Christian Vincenzo Traina, Commented May 26, 2022 at 7:31

Bruno Polo · Accepted Answer · 2022-05-24 17:35:48Z

2

I think your approach is just fine. You could create a function, and check array length before trying to read element at index 0:

utils.js


export const removeFirstItemIfEmpty = (array) => {
    if (array.length > 0 && array[0] == '') {
        array.shift();
    }
    return array;
}

import { removeFirstItemIfEmpty } from './utils.js'

const result = removeFirstItemIfEmpty(['', 'not', 'empty', 'value']);
console.info({ result });

answered May 24, 2022 at 17:35

Bruno Polo

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Comments

Guruprasad J Rao · Accepted Answer · 2022-05-26 07:22:32Z

1

You could use filter and update the array.

specialtiesListArray = ['', 'not', 'empty', 'value'];
specialtiesListArray = specialtiesListArray.filter((item, index) => index!==0 && item !== '');
console.log(specialtiesListArray);

edited May 26, 2022 at 7:22

answered May 24, 2022 at 17:30

Guruprasad J Rao

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4 Comments

Bruno Polo Over a year ago

This would remove not just the first element

Mister Jojo Over a year ago

this does not remove the empty elements, but it creates a new array (without them) which replaces the original array...

Guruprasad J Rao Over a year ago

@BrunoPolo - Now it does :)

Bruno Polo Over a year ago

@GuruprasadJRao if verification is only needed in first element, there is no need to check all items in array (Array.filter will loop through all items)

Carsten Massmann · Accepted Answer · 2022-05-24 17:43:48Z

0

The following function will remove anything that is undefined, null or empty but will allow the number 0 to pass:

var testArr = [['', null, 'not', 'empty', 'value'],[false,2,3,4],[undefined,"", null,"one","two"],[0,1,2,3]];

function ltrimArr(arr){
 while (arr.length && !arr[0]&&arr[0]!==0) arr.shift();
 return arr
}

testArr.forEach(a=>console.log(ltrimArr(a)))

answered May 24, 2022 at 17:43

Carsten Massmann

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