javascript简写（如果else回调）

Question

the long hand if in javascript would look:

function somefunction(param){

    if(typeof(param) != 'undefined'){
           var somevar = param;
         } else {

           alert('ERROR: missing parameter in somefunction. Check your form'); 
           return;

         }

}

AND MY SHORT HAND VERSION IS:

function somefunction(param){

    param = typeof(param) != 'undefined' ? param : function(){alert('ERROR: missing parameter in somefunction. Check your form'); return;}

}

BUT it does not work.

How could I?

Thank you

Answer 1

You are only declaring the function. you have to execute it. Add () next to the definition ..

function somefunction(param){
    param = typeof(param) != 'undefined' ?
                param :
                function() {
                    alert('ERROR: missing parameter in somefunction. Check your form'); 
                    return false;
                }();
}

EDIT: The above is not functionally equivalent to the original as the function itself doesn't return anything and doesn't end the function execution.

function somefunction(param) {
    if (typeof(param) == 'undefined') {
        alert('ERROR: missing parameter in somefunction. Check your form'); 
        return false;
    }

    // Use param
}