javascript multidimensional array is valid

Question

I have an array that looks kind of like this memory[indexGroup][indexItem]. How can I check if that is valid, in other words if it would work when using console.log and getting a value back, not null, undefined or other non values. Empty, 0 and false are valid. These don't give errors.

This is what I ended up with (seems to work) but it's a mess:

function hasMemory() {
    if( typeof memory === 'undefined') return;
    if( typeof memory[indexGroup] === 'undefined') return;
    if( memory[indexGroup] === null ) return;
    if( typeof memory[indexGroup][indexItem] === 'undefined') return;
    if( memory[indexGroup][indexItem] === null) return;
    if( memory[indexGroup][indexItem] !== true ) return;
    return true;
}

Scenarios

memory is not set
memory[indexGroup] is not set
memory[indexGroup][indexItem] is not set

Then it should just return but if the full multidimensional array is valid, it should return true.

Is there a shorter/better/safer ways to check this?

function hasMemory(){ return Boolean(memory && memory[indexGroup] && memory[indexGroup][indexItem]) } — Thomas
– Thomas, Commented Jan 27, 2017 at 20:32

Vladu Ionut · Accepted Answer · 2017-01-27 23:10:16Z

2

function hasMemory() {
return memory && memory[indexGroup] && memory[indexGroup][indexItem]
}

To handle the case where memory[indexGroup][indexItem] is 0 or false, based on

undefined == null
null == undefined

you can add to condition memory[indexGroup][indexItem]!=null

edited Jan 27, 2017 at 23:10

answered Jan 27, 2017 at 20:30

Vladu Ionut

8,2231 gold badge24 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Jens Törnell Over a year ago

So it checks if these values are... what? Valid values?

Kevin Jantzer Over a year ago

This would check if undefined, null, 0 or empty string. So the logic will break down if you need to accept something other than undefined/null

Mike Cluck Over a year ago

This doesn't handle the case where memory[indexGroup][indexItem] is 0 or false. Also, there's no reason to return true or false. It's functionally equivalent to doing return (true) ? true : false.

Mike Cluck · Accepted Answer · 2017-01-27 20:49:46Z

1

You can check for both null and undefined simultaneously by performing a loose check against null but will not work for 0 or false.

var u = undefined;
var n = null;
var z = 0;
var f = false;
console.log(u == null);
console.log(n == null);
console.log(z == null);
console.log(f == null);

Using that, here's a shorter way of approaching this:

function hasMemory() {
  return memory &&
         memory[indexGroup] != null &&
         memory[indexGroup][indexItem] != null;
}

edited Jan 27, 2017 at 20:49

answered Jan 27, 2017 at 20:40

Mike Cluck

32.6k13 gold badges84 silver badges95 bronze badges

Collectives™ on Stack Overflow

javascript multidimensional array is valid

Scenarios

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Scenarios

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related