Oh...How can I attack the units in front of me by ability?

Hi~
First I want to say that I'm a little student in China.So my English is poor...
Chinese new year is coming,hope you happy~
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In China there is a wc3 map named Darkdancer,player may use keyboard to attack .I think it's interesting so I want to ask a question:
How can I attack the units in front of me by ability?
(For example ,click on "W" then attack my enemies for one time then stop.)
look,enemies are attacked who teach his weapon!
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thank you ~~

who can tell me?

It's pretty easy, the way I am going about it in my map is just a simple spell that does nothing but is triggered. So make a spell with the hotkey w and when the player presses it play the attack animation then check for units in front of the unit and play like an effect on the unit to show its hit and a sound, also add the damage to it of course.

Thanks a lot !Let me try in my map .
I'm a beginner:)