2.1.97 [HTML5:2014] Section 4.11.4.2 Serializing bitmaps to a file

V0220: Setting the JPEG quality to an invalid value does not cause the default value to be used

The specification states:

 ... Serializing bitmaps to a file
     ...
     Arguments for serialization methods [table]
  
         Other arguments [column]
  
             The second argument, if it is a number in the range 0.0 to 1.0 inclusive, 
             must be treated as the desired quality level. If it is not a number or is 
             outside that range, the user agent must use its default value, as if the 
             argument had been omitted.

All document modes (All versions)

Setting the JPEG quality to an invalid value does not cause the default value to be used.