What's the difference between is_null($var) and ($var === null)?

✅ is true

❌ is false

        | isset   | is_null | ===null | ==null  | empty   |
|-------|---------|---------|---------|---------|---------|
|  null |    ❌   |    ✅   |    ✅   |    ✅  |    ✅   |
|  true |    ✅   |    ❌   |    ❌   |    ❌  |    ❌   |
| false |    ✅   |    ❌   |    ❌   |    ✅  |    ✅   |
|     0 |    ✅   |    ❌   |    ❌   |    ✅  |    ✅   |
|     1 |    ✅   |    ❌   |    ❌   |    ❌  |    ❌   |
|    \0 |    ✅   |    ❌   |    ❌   |    ❌  |    ❌   |
| unset |    ❌   |    ✅   |    ✅   |    ✅  |    ✅   |
|   ""  |    ✅   |    ❌   |    ❌   |    ✅  |    ✅   |

Summary:♦️

• empty is equivalent to ==null
• is_null is equivalent to ===null
• isset is inverse of is_null and ===null

Provided the variable is initialized (which you did indicate - though I'm not 100% sure if this matters in this context or not. Both solutions might throw a warning if the variable wasn't defined), they are functionally the same. I presume === would be marginally faster though as it removes the overhead of a function call.

It really depends on how you look at your condition.

=== is for a strict data comparison. NULL has only one 'value', so this works for comparing against NULL (which is a PHP constant of the null 'value')

is_null is checking that the variable is of the NULL data type.

It's up to you which you choose, really.

Both are exactly same, I use is_null because it makes my code more readable