Button that resets score to zero in corona

Question

I am trying to learn corona. I have created a sample application, where it increases the score by 1, every time you click the balloon. I have added a button, wherein if you click, the score should go back to 0.

local tapCount = 0
local widget = require "widget"

local background = display.newImageRect( "background.jpg", 700,1075)
background.x = display.contentCenterX
background.y = display.contentCenterY

local tapText = display.newText( tapCount, display.contentCenterX, 20, native.systemFont, 40 )
tapText:setFillColor( 0, 0, 0 )

local platform = display.newImageRect( "panel.png", 300, 50 )
platform.x = display.contentCenterX
platform.y = display.contentHeight-25

local balloon = display.newImageRect( "baloon.png", 112, 112 )
balloon.x = display.contentCenterX
balloon.y = display.contentCenterY
balloon.alpha = 0.8

local physics = require( "physics" )
physics.start()

physics.addBody( platform, "static" )
physics.addBody( balloon, "dynamic", { radius=50, bounce=0.3 } )

local myButton=widget.newButton{
    --The id can be used to tell you what button was pressed in your    button event
    id = "myTextButton",
    --This is the text label to put on the button
    label = "Reset",
    --This is the start x coordinate of the Top Left Corner
    left = 150,
    --This is the start y coordinate of the Top Left Corner
    top = 150,
    --Emboss can be true or false, tells it to make the label look embossed/inset
    emboss = true,
    --The border around the outside of the button
    strokeWidth = 4,
    --How round to make the corners
    cornerRadius = 8,
    --this tells it what function to call when you press the button
    onEvent = myButtonEvent
}


local function pushBalloon()
    balloon:applyLinearImpulse( 0, -0.75, balloon.x, balloon.y )
    tapCount = tapCount + 1
    tapText.text = tapCount
end

local myButtonEvent = function (event )
    if (event.phase == "release") then
        tapCount = 0
        tapText.text = tapCount
    end
end
balloon:addEventListener( "tap", pushBalloon )

Answer 1

From Corona documentation

onEvent (optional) Listener. An optional function that should only be specified if onPress and onRelease are not set. This callback function allows you to test for the event.phase of "began", "moved", or "ended".

So try

Method one: Put definition of myButtonEvent function before you use it name in code.

local myButtonEvent = function (event )
    if (event.phase == "ended") then
        tapCount = 0
        tapText.text = tapCount
    end
end

local myButton=widget.newButton{
    --The id can be used to tell you what button was pressed in your    button event
    id = "myTextButton",
    --This is the text label to put on the button
    label = "Reset",
    --This is the start x coordinate of the Top Left Corner
    left = 150,
    --This is the start y coordinate of the Top Left Corner
    top = 150,
    --Emboss can be true or false, tells it to make the label look embossed/inset
    emboss = true,
    --The border around the outside of the button
    strokeWidth = 4,
    --How round to make the corners
    cornerRadius = 8,
    --this tells it what function to call when you press the button
    onEvent = myButtonEvent
}

Method two: Use forward declaration.

local myButtonEvent -- put on top of file