easiest way: condition - real - math - istance between points - distance of unit
try using the gui more often and you'll quickly realise that it is often more usefull than jass - i do 1/2 o fmy triggers with the gui making them easier to understand...
xto = X location of position your measuring from yto = Y location of position your measuring from xfrom = X location of position your measuring to yfrom = Y location of position your measuring to
Using this will save you having to remove the location and creating a local location since it takes reals (x and y).
I recomend you use jass since propper jass can be less laggy than GUI since GUI calls unesesary BJ calls and creats functions for conditions that are NOT nesesary.
Also non jass aided GUI will leak when using groups, locations, and forces.
I strongly reccomend you program MOST triggers in jass since you can reduce not only the number of lines the script takes up but write it more efectivly.
A good example of GUI triggering is the parasite chain. It leaks badly, is very buggy, extremely laggy, and a ---- load of unessary function and BJ calls.