Get The Last Non-null Element Of An Array

Having an array like this myArray = ['test', 32.5, 11.3, 0.65, 533.2, null, 423.2, null, null]; is there a way to get the last non-null element? In this case it should be 423.2.

Solution 1:

The easiest way of doing this is to filter out the null items using .filter, and then get the last element using .slice:

lastNonNull = myArray.filter(x => x != null).slice(-1)[0]
console.log(lastNonNull) // 432.2

To break this down a bit:

myArray
    .filter(x => x != null)    // returns ["test", 32.5, 11.3, 0.65, 533.2, 423.2]
    .slice(-1)                 // returns [423.2]
    [0]                        // returns 423.2 

Solution 2:

Another way is Array#reduce():

var myArray = ["test", 32.5, 11.3, 0.65, 533.2, null, 423.2, null, null];
var last = myArray.reduce((acc, curr) => curr ? curr : acc);
console.log(last);

Solution 3:

Use reverse and find

["test", 32.5, 11.3, 0.65, 533.2, null, 423.2, null, null].reverse().find( s => s != null )

Or just one reduceRight

var arr = ["test", 32.5, 11.3, 0.65, 533.2, null, 423.2, null, null]
arr.reduceRight( (a,c) => ( c != null && a == null ? c : a) , null)

Solution 4:

You can use filter to filter the non null elements and use pop to get the last element.

let myArray = ["test", 32.5, 11.3, 0.65, 533.2, null, 423.2, null, null];
let result = myArray.filter( v => v !== null ).pop();
  
console.log( result );