How to determine the length of a .gif animation in milliseconds

Question

Is there an easy way to figure out approximately how long a .gif image takes to play one time in Javascript?

Answer 1

The identify command from ImageMagick can give this information:

$ identify -verbose file.gif | grep 'Elapsed time'

  Elapsed time: 0:01.080
  Elapsed time: 0:01.150
  Elapsed time: 0:01.230

...

  Elapsed time: 0:04.250
  Elapsed time: 0:04.330
  Elapsed time: 0:04.399
  Elapsed time: 0:04.480

The last line printed should be the total length of the animation.