Question

function (){
    alert('a function');
}

when i put it on the firebug javascript control. it shows function statement requires a name

(function (){
    alert('a function');
}())

when i put the above it shows ok.

function (){
    alert('a function');
}()

it also shows function statement requires a name and doesn’t execute the function. why?

Answer 1

function (){
    alert('a function');
}

is a function statement, so it requires a name.

(function (){
    alert('a function');
}())

The () change the statement to an expression, so it’s OK.

And you could also use the below ways.

(function (){
    alert('a function');
})();

!function (){
    alert('a function');
}();

+function (){
    alert('a function');
}();