This is my script, Kinematic body 2D. I want to add double jump, can anyone help ?

Gio_k

const ACCELERATION = 0
const MAX_SPEED = 64
const FRICTION = 0
const AIR_RESISTANCE = 0
const GRAVITY = 1500
const JUMP_FORCE = 750

var motion = Vector2.ZERO

func _ready():
	pass

func _physics_process(delta):
	if motion.y >0:
		motion.y += GRAVITY * delta * 2
	else:
		motion.y += GRAVITY * delta

	if is_on_floor():
		if Input.is_action_just_pressed("Jump"):
			motion.y = -JUMP_FORCE
	else:
		if Input.is_action_just_released("Jump") and motion.y < -JUMP_FORCE/2:
			motion.y = -JUMP_FORCE/2
	motion = move_and_slide(motion, Vector2.UP)

ProbablyTooAmbitious

Hopefully this should work:

extends KinematicBody2D

const ACCELERATION = 0
const MAX_SPEED = 64
const FRICTION = 0
const AIR_RESISTANCE = 0
const GRAVITY = 1500
const JUMP_FORCE = 750
var double_jump = false
var motion = Vector2.ZERO

func _physics_process(delta):
	if motion.y > 0:
		motion.y += GRAVITY * delta * 2
	else:
		motion.y += GRAVITY * delta
	if is_on_floor():
		double_jump = false
		if Input.is_action_just_pressed("Jump"):
			motion.y = -JUMP_FORCE
	else:
		if Input.is_action_just_pressed("Jump"):
			if double_jump == false:
				motion.y = -JUMP_FORCE
				double_jump = true
		if Input.is_action_just_released("Jump") and motion.y < -JUMP_FORCE/2:
			motion.y = -JUMP_FORCE/2
	motion = move_and_slide(motion, Vector2.UP)