Double Jumps In Vanilla Minecraft Commands

Commands for Double Jump Below
1. Setup the scoreboards
> /scoreboard objectives add jump stat.jump
> /scoreboard objectives add jump2 dummy

2. Make Fill Clock
> /fill ~-1 ~ ~-3 ~-1 ~ ~ redstone_block
> /fill ~1 ~ ~-3 ~1 ~ ~ stone

3. Put these commands onto fill clock
> /effect @a[score_jump2_min=1] 8 5 2 true
> /scoreboard players set @a[score_jump_min=2] jump 0
> /scoreboard players set @a jump2 1

4. Put the testfor command on the fill clock and connect a comparator to it and a repeater set to 2 ticks (Right-click the repeater 2 times)
> /testfor @a[score_jump2_min=1,score_jump_min=1]

5.Connect to Output
> /execute @a[score_jump_min=1,score_jump2_min=1] ~ ~ ~ /fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 barrier 0 replace air 0

6. Reset and remove barriers
> /execute @a ~ ~ ~ fill ~-6 ~-6 ~-6 ~6 ~6 ~6 air 0 replace barrier 0
> /scoreboard players set @a jump 0

Trouble? Need Help? Check out the YouTube explanation: https://www.youtube.com/watch?v=bFOPNTbFEjQ