Question

Given this function:

function foo( a,b,c ) {
    //
}

How can you do something, say use console.log() for each argument? I know you can see the arguments by using the arguments keyword. Arguments seems to return what looks like an Array (but is of type “object” [suprise.. not]) but it doesn’t support .forEach, I am using Chrome.

I tried modifying the function to this, and expected it to work:

function foo( a,b,c ) {
    arguments.forEach(function( arg ){
        console.log( arg );
    });
}

You get the error that TypeError: Object # has no method ‘forEach’.

Answer 1

The arguments object doesn’t have a forEach method, so you need to iterate over it either with a for loop, or a for...in loop.

​function foo () {
    for (var i = 0; i < arguments.length; i++) {
        console.log(arguments[i]);    
    }
}

foo("Foo", { "bar": 0 }); // Output: Foo, Object {bar: 0} 

Or

​function foo () {
    for (var arg in arguments) {
        console.log(arguments[arg]); 
    }    
}

foo("Foo", "Bar"); // Output: Foo, Bar