Trying to make an invisible armor datapack, struggling with if conditions.

The premise is simple really, check if the item the player is holding is a piece of armor, and if it is, make it invisible.
This function works for a helmet:
execute as @s if items entity @s weapon *[minecraft:equippable] run item modify entity @s weapon {function:"minecraft:set_components", components: {"minecraft:equippable": {slot:'head', model:'air'}}}


The problem here is that I seemingly HAVE to specify the slot of the armor piece, so I have to paths in my mind. 


    

  1. Do like 4 if statements (but how?) to check for the armor type and then execute the proper command, no clue how to do this.
or
    2. 

  2. Somehow inherit the slot value, which seems easier.
    3. 



Would really appreciate some help, I am a total novice at this.
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