This is one of the key problems with the code. It checks whether tiger.y is exactly 120 but doesn’t account for when tiger.y passes 120.
You can see here that tiger.y never actually hits 120 and skips from 119 to 123.
tiger.y >= 30 is also wrong and it should be tiger.y <= 30
tiger.y == 120 should be changed to the opposite (greater than or equal to): tiger.y >= 120
After these edits, you may find that the tiger is not actually moving, that’s because tiger.y is 31. Simply go to line 8, where it says: var tiger = createSprite(46, 31) and change 31 to 30.
Here are the changes