toString() and IE

[jarno_rossi]

hi, I know that utag.js use ".toString()" method (i.e. with load rules), but I also know that IE does not support that method, so I guess that in many cases utag.js stops running due to IE-error. Does it make sense on you? Do you have any evidence of that? Or am I wrong? Thanks,

[craig_rouse · Accepted solution]

Hi Jarno, IE does support the toString method. However, your load rule may fail if it attempts to do a toString on an undefined variable e.g. if your load rule says "page_name contains ignore case 'test'", then if page_name is not defined, you'll get an uncaught error: "Cannot call method toString of undefined" or something similar. To avoid this, it's best to add a check to the load rule that the variable is defined before trying to perform a comparison on it: i.e. "page_name IS DEFINED AND page_name contains_ignore_case 'test'". I hope this helps to explain what's going on. Craig.

[simon_browning]

Hi Jarno, toString() is support from IE6 up. Please see documentation about this on the IE Dev Centre: http://msdn.microsoft.com/en-us/library/ie/k6xhc6yc(v=vs.94).aspx Hope this helps. Kind Regards Simon

[jarno_rossi]

Ok thanks.

[jarno_rossi]

Great, I see now... So it's a good practice to add a "DEFINED" or "NOTDEFINED" condition at the beginning of any load rules? otherwise we occur in the following problem: we need to load a Z tag when X does not contain Y. If X does not exist, the condition is TRUE, but we get an javascript error instead.

[craig_rouse]

Correct - if you're testing for a value in a variable, it's a good idea to make sure it is defined first. Adding the DEFINED check will protect against the case where your variable does not exist.

[kevin_faurholt]

IS POPULATED is also a good one. It checks for the data source is defined AND it has a value.

[jarno_rossi]

great tip!