TypeError: Cannot set property 'innerHTML' of null

Question

Here is my code: It works fine if I code a string directly into the thisLocation value, eg "A2".
But if I allow thisLocation to get its value from the array I get a TypeError: Cannot set property 'innerHTML' of null.
However even though I get the error the alert box still dsiplays the thislocation value correctly.

var arr = letters.split("|");
var thisImage;
var thisLocation;

for(i =0; i < arr.length; i++){
thisLocation = arr[i];
alert("thisLocation is " + thisLocation );
document.getElementById(thisLocation).innerHTML = "<img src=" + thisImage + ">";
}

Answer 1

Copy your entire code to CodePlayground and link it here.
In your arr you have strings that don't match any DOM object id.

Temporary solution:
var el = document....(thisLocation);
if(el){
el.innerHTML = ".....";
}

Link your code.

Answer 2

Thanks very much Kevin. That solved it for me.