var exclude = /z-?index|font-?weight|opacity|zoom|line-?height/i;
// Handle passing in a number to a CSS property
- if ( value.constructor == Number && type == "curCSS" && !exclude.test(prop) )
+ if ( value && value.constructor == Number && type == "curCSS" && !exclude.test(prop) )
return value + "px";
return value;