Question

I’have the next array:

[null,null,null,null,null,null,2,10,29,43,45,40,54,39,13,1,null,null,null,null,null]

I need to know what is the first position in that array that is NOT null and the last that is NOT null too.

In this particular example, first will be 6 (counting 0 as position 1) and 15.

Thank you

Answer 1

var firstPos = -1, lastPos = -1;
for(var i = 0; i < arr.length; i++) {
    if(arr[i] !== null) {
        if(firstPos == -1) {
            firstPos = i;
        }
        lastPos = i;
    }
}