Steps to reproduce

1. Be in a flat area with no other mobs around.
2. Turn on coordinates.
3. /effect @s resistance 28800 4 true
4. /time set midnight
5. /summon spider
6. Slowly walk backwards each in cardinal direction while the spider attacks you.

Expected result

The spider frequently jumps while attacking.

Observed result

The spider only jumps while attacking if the player is in the -X or -Z direction.

Since many versions I’ve notice spiders' behavior while attacking seemed a bit strange, and finally I have found out it is due to a bug. Checking java edition, the difference is quite noticeable after watching spiders syncing attacks in middle air after jumping at close range. On bedrock edition they just chase and hit you independently of how close they are from you, and sometimes rarely jump, but always attacking either after or before jumping.  

If java edition isn’t enough proof as example to how the expected behavior should work, here I bring the Minecraft wiki: 

An aggressive spider pounces at close range. They can attack when their Y-axis position is changed, biting in mid-air. 

YT video from bedrock edition:

https://youtu.be/9_AXLdGFA3k

YT video from java edition to notice the miss-match:

https://youtu.be/MO2usvrXeUE