Question

I am having a weird problem here.

I am trying to check if the variable exists

I have

for(var i=0; i<6; i++{
  if(results[(i+1)].test){
    results[(i+1)].test=i + 'test';
  }
}

I know results(6).test is undefined and I need to add that extra index to check if the variable exists. I keep getting console error saying

Uncaught TypeError: Cannot read property 'test' of undefined   

I thought if(results[(i+1)].test) would check if the variable exists for me

I also tried

if(typeof results[(i+1)].test !='undefined'){
 results[(i+1)].test=i + 'test'
}

but still getting error. How do I fix this?

Thanks a lot!

Answer 1

You’re checking whether foo.test is undefined, but your problem is that foo itself (in this case results[i + 1]) is undefined.

You need to check that first, eg.:

if (typeof results[i+1] != "undefined") {
    // do stuff with results[i+1].test, or results[i+1].whatever
}