DMI Indicator: How do I create alerts

If you want to learn how to do these I suggest you spend time browsing the solutions in the "Stock Scanner" topic. Why? Because a scan is a true/false condition. True for a handful of bars where the condition is valid and false for the rest of the bars on the chart. That is the foundation for every study that plots arrows on the price graph. In fact they can be directly converted from one to another with some very simple adjustments to the code.

Check the previous post I found in the "Stock Scanners" topic. Be sure to read all the details on that page so you understand the context and the solution.

https://www.hahn-tech.com/ans/scan-dmi-plus-crosses-dmi-minus/

Now I'll show you how to convert that to a chart study that plots arrows on the upper price graph. Here is the code I directly copied from that post, excluding the four lines of code at the very bottom that constitute the signals used specifically for the scan:

input length = 14;
input averageType = AverageType.WILDERS;
input threshold = 20;
def hiDiff = high - high[1];
def loDiff = low[1] - low;
def plusDM = if hiDiff > loDiff and hiDiff > 0 then hiDiff else 0;
def minusDM = if loDiff > hiDiff and loDiff > 0 then loDiff else 0;
def ATR = MovingAverage(averageType, TrueRange(high, close, low), length);
def diPlus = 100 * MovingAverage(averageType, plusDM, length) / ATR;
def diMinus = 100 * MovingAverage(averageType, minusDM, length) / ATR;
def DX = if (diPlus + diMinus > 0) then 100 * AbsValue(diPlus - diMinus) / (diPlus + diMinus) else 0;
def diPlusCrossesAbove = diPlus[1] < diMinus[1] and diPlus > diMinus;
def diPlusCrossesBelow = diPlus[1] > diMinus[1] and diPlus < diMinus;

This is your foundation. Everything you need to complete this is right there. You only need to change the last two lines from "def" to "plot" and add the style statements that configure those plots to paint arrows on the price graph. Here are those last two lines from the code above, modified as I just described:

plot diPlusCrossesAbove = diPlus[1] < diMinus[1] and diPlus > diMinus;
diPlusCrossesAbove.SetPaintingStrategy(PaintingStrategy.BOOLEAN_ARROW_UP);
plot diPlusCrossesBelow = diPlus[1] > diMinus[1] and diPlus < diMinus;
diPlusCrossesBelow.SetPaintingStrategy(PaintingStrategy.BOOLEAN_ARROW_DOWN);

Done. Yep, it is that simple. I have taken the last two lines from the foundational code and adapted them to display as up and down arrows on the chart. The final and complete solution is to take these four lines of code and use them to replace the last two lines from our foundational code:

input length = 14;
input averageType = AverageType.WILDERS;
input threshold = 20;
def hiDiff = high - high[1];
def loDiff = low[1] - low;
def plusDM = if hiDiff > loDiff and hiDiff > 0 then hiDiff else 0;
def minusDM = if loDiff > hiDiff and loDiff > 0 then loDiff else 0;
def ATR = MovingAverage(averageType, TrueRange(high, close, low), length);
def diPlus = 100 * MovingAverage(averageType, plusDM, length) / ATR;
def diMinus = 100 * MovingAverage(averageType, minusDM, length) / ATR;
def DX = if (diPlus + diMinus > 0) then 100 * AbsValue(diPlus - diMinus) / (diPlus + diMinus) else 0;
plot diPlusCrossesAbove = diPlus[1] < diMinus[1] and diPlus > diMinus;
diPlusCrossesAbove.SetPaintingStrategy(PaintingStrategy.BOOLEAN_ARROW_UP);
plot diPlusCrossesBelow = diPlus[1] > diMinus[1] and diPlus < diMinus;
diPlusCrossesBelow.SetPaintingStrategy(PaintingStrategy.BOOLEAN_ARROW_DOWN);

Screenshot below shows how this looks on the chart.