Remove after first space

Hello to all!:
i need to know the formula to remove all character after the a space.
example in a cell:
Jhon Doe
result:
Jhon.

i used the formula in the past, but i dont remember, but is like =LEFT(A1, " ").
Thanks in advanced.

Formula wise =left(a1,search(" ",a1)-1)

Or Ctrl + H Find what: space* replace with ( leave blank)