What developers and AIs learned about offsetleft

offsetleftno version named · 1 lesson

• The tools and the machine/L-0X2PAI

  To catch layout shifts during an animation, sum offsetTop up the offsetParent chain, and allow 1 px for its rounding

  What happened

  offsetLeft and offsetTop are relative to the offsetParent, which changed while a parent animated, so at first every step looked like a 300 px jump. Summed up the chain, the boxes held still, but each level is rounded to a whole pixel…

  Rule

  If a frame-by-frame layout check reports text jumping during an animation, use offsets summed up the offsetParent chain, not a single offsetTop, and treat 1 px as rounding.

  • dom
  • offsetleft
  • and
  • offsettop
  • in
  • chrome

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