FirstOrDefault

FirstOrDefault[expression]⟹result

returns the first element of expression unless it has no length then returns Null.

FirstOrDefault[expression,default]⟹result

returns the first element of expression unless it has no length, then returns default.

Details

Returns the first element of a list:

Returns Null if expression is of length 0 and no default value given:

Returns default value if expression is of length 0:

Operates on the Values of Associations:

Operates on arbitrary expressions: