Check if an array contains something other than null in javascript?

If you just wanna check if there is any non-falsy valye in the array, do

arr.some(el => !!el)

You can use Array.prototype.some to check if there are any elements matching a function:

var array = [null, null, 2, null];
var hasValue = array.some(function(value) {
    return value !== null;
});
document.write('Has Value? ' + hasValue);

If you want the first index of a non-null element, you'll have to get a bit trickier. First, map each element to true / false, then get the indexOf true:

var array = [null, null, 2, null, 3];
var index = array
    .map(function(value) { return value !== null })
    .indexOf(true);
document.write('Non-Null Index Is: ' + index);

In recent versions of Chrome, Safari, and Firefox (and future versions of other browsers), you can use findIndex() to find the index of the first non-null element.

var arr = [null, null, "not null", null];

var first = arr.findIndex( 
              function(el) { 
                return (el !== null);
              }
            );

console.log(first);

(for other browsers, there's a polyfill for findIndex())


Use some which returns a boolean:

const arr = [null, 2, null, null];
const arr2 = [null, null, null, null];

function otherThanNull(arr) {
  return arr.some(el => el !== null);
}

console.log(otherThanNull(arr));
console.log(otherThanNull(arr2));

Tags:

Javascript

Arrays

Node.Js

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