How do I apply potion effects to a player wearing armor with a special name with command blocks

Question

I am making special classes for my server, and I want to give someone underwater breathing whenever they are wearing a helmet named scuba. How do I do this with command blocks?

Answer 1

What you could do is /testfor a player with a helmet with a custom name scuba. Test for the slot number they have it in, (helmets are 103) This command should do all that:

/testfor @p[r=2] {Inventory:[{Slot:103b,tag:{display:{Name:"scuba"}}}]}

Hook it up to a clock of your choice and if the /testfor command reads true then have a comparator ready to activate a sticky piston that pushes a redstone block to activate the command

/effect @p minecraft:water_breathing

When they leave your set radius or remove there helmet the sticky piston will deactivate pulling the redstone block activating the command

/effect @p clear

This is a list of the inventory slot numbers.

The Youtuber Dragnoz also has a great video on how to do things like this.