if isset javascript equivalent

[Genesis5150]

I'm looking for a solution for the javascript version of if isset in php. This is what I have:

if (typeof obj.office !='') 
  	{( document.listingform.office.value.length < 3 ); 
		{ if (valid)
      document.listingform.office.focus();
    document.listingform.office.style.border="solid 1px red";
    msg+="\"Office\" field cannot contain less than three characters\n";
    valid = false;
  }
	}

What I want to to do is if the field "office" holds a value and is less than three characters then alert but only if it has a value. How can I do that.

[requinix]

"isset" isn't the thing you're looking for, then. Because the thing exists.

 

Just check for an empty value.

[Genesis5150]

Thanks for the advice I went on and tried this but no luck:
 

if (obj.office && obj.office.length < 3) {
    if (valid)
      document.listingform.office.focus();
    document.listingform.office.style.border="solid 1px red";
    msg+="\"Office\" field cannot contain less than three characters\n";
    valid = false;
  }

[requinix]

I don't know where valid or obj.office are coming from, but what I meant was a simple

document.listingform.office.value == ""