Value Does not update in real time

i have a condition ,when a candle hits a target the value which was false become true and alert fires,
problem is when it hits the target several time in same time frame in 1 candle the value remains same and alert keeps on comming till that candle is closed.
i tried using variable with var keyword also with varip keyword

if(crossunder(close,trailprice) and trailprice!=0.0 and long==false)
long:=true
alert(you hit the target)

this code keeps on running on same bar even if long becomes true

try this

if(crossunder(close,trailprice) and trailprice!=0.0 and long==false)
long:=true
           alert("you hit the target", alert.freq_once_per_bar_close)

Documentation: https://www.tradingview.com/pine-script-reference/v4/#fun_alert

did not worked