Help with return values challenge

(erf, my previous answer disapeared, wrong manipulation). Your if comparison is the same as writing if ("undefined") {} because the comma in Javascript return the last operand (in your case, "undefined"). You should try another structure (like if...else if...else).

If you have to check for multiple conditions you have to use the or-operator ( || ) to achieve your desired result. For example:

var n = 10;
if( n < 9 || n * n > 99 ) {
    // Do something..
}

I tried it in the code engine, but it said I hadn't defined a function called arrayCounter, so that didn't work, but it should (I think)..

EDIT: I had written “array typeof === "string" (etc ..)” instead of “typeof array === "string" (etc...)”, it worked after I corrected it. And, you could also use a single | to represent the or-operator (see Giovanni's post). Thanks for the enlightenment, Giovanni! :)

But, another way, and maybe a better way too, is to check if the argument is an instance of Array (note capital “a”). Like this:

function arrayCounter(array) {
    if(array instanceof Array) {
        return array.length;
    } else {
        return 0;
    }
}

Hi Knut, in some other languages you use ||, in javascript you use the single | (then it will work).

function counterArray(array) {
        if (typeof array ==="string" | typeof array ==="number" | typeof array==="undefined") {
          return 0 ;
        } else {
            return array.length ; 
        }
      } 

Another option would be the if...else if...else...

function counterArray(array) {
        if (typeof array ==="string") {
          return 0 ;
        } else if (typeof array ==="number") {
          return 0 ;
        } else if (typeof array ==="undefined") {
          return 0 ;
        } 
       else {
            return array.length ; 
        }  

Well, I don't know how to format my code like you all, if you could tell me ^^, my answers would be clearer.

EDIT: ok got it :), now it's much clearer.

Check out the following code snippet:

var arr_1 = [1, 2, 3, 4];
var name = "John Doe";

if( arr_1 instanceof Array ) {
    console.log("This will be written since arr_1 is an instance of the object prototype Array");
}

if( name instanceof Array) {
    console.log("This will not be written since the variable name is not an instance of the object prototpye Array");
}

Since arr_1 is an instance of the Array-object, the instanceof-operator returns true. The name variable, on the other hand, is not an instance of the Array-object, thus the instanceof-operator returns false.

Check out more examples for instanceof here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof