PineScript v2 to v4

Question

I've coded this pinescript a couple of year ago with little knowledge to code, I still dont have much coding knowledge and things seem to have updated and wondering if anyone can help me update my script to Version 4 or 5 of the pine script version. Thanks in advance.

strategy("Heikin Strategy",shorttitle="HeikStrat",overlay=true,max_bars_back=50,default_qty_type=strategy.cash,initial_capital=100,currency=currency.USD)
res1 = input(title="Heikin Ashi EMA Time Frame", type=resolution, defval="D")
test = input(1,"Heikin Ashi EMA Shift")
sloma = input(20,"Slow EMA Period")

// MA (Kaufman)
Length = input(5, minval=1)
xPrice = input(hlc3)
xvnoise = abs(xPrice - xPrice[1])
Fastend = input(2.5,step=.5)
Slowend = input(20)
nfastend = 2/(Fastend + 1)
nslowend = 2/(Slowend + 1)
nsignal = abs(xPrice - xPrice[Length])
nnoise = sum(xvnoise, Length)
nefratio = iff(nnoise != 0, nsignal / nnoise, 0)
nsmooth = pow(nefratio * (nfastend - nslowend) + nslowend, 2) 
nAMA = nz(nAMA[1]) + nsmooth * (xPrice - nz(nAMA[1]))

//Heikin Ashi Open and Close Price
ha_t = heikinashi(tickerid)
ha_close = security(ha_t, period, nAMA)
mha_close = security(ha_t, res1, hlc3)

//Moving Average
fma = ema(mha_close[test],1)
sma = ema(ha_close,sloma)
plot(fma,title="MA",color=yellow,linewidth=2,style=line)
plot(sma,title="SMA",color=red,linewidth=2,style=line)

//Strategy longs
golong =  crossover(fma,sma) 
longexit =   crossunder(fma,sma)

goshort = crossunder(fma,sma)
shortexit  = crossover(fma,sma)

strategy.entry("Buy",strategy.long,when = golong)
strategy.close("Buy",when = longexit)

strategy.entry("Sell", strategy.short, when = goshort)
strategy.close("Sell",when = shortexit)

Answer 1

In Pine Script v4 it's no longer possible to create variables with an unknown data type at the time of their declaration. You must change it manually.

You can read the conversion guide here

So if v3 is like this

nAMA = nz(nAMA[1]) + nsmooth * (xPrice - nz(nAMA[1]))

In v4 it should be like this

nAMA = 1.0
nAMA := nz(nAMA[1]) + nsmooth * (xPrice - nz(nAMA[1]))

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And be careful with Backtesting on Non Standard Charts (Heikin Ashi)

Read this