Object only has strings detection

Question

I have this problem that I can't figure out how to determine if the object only has strings. I am trying not only to get help on figuring this out, but if someone has time, they could explain why their answer works, to help me learn. Thank you

function hasOnlyStrings(o) {
 for (var val in o) {
   var values = o[match];
     if (typeof values === 'string') {
        return true;
     } 
     else { return false; }
 }
}

var car = {
 name: 'corvette',
 fast: true,
 color: 'black'
}

var truck = {
 name: 'ford',
 color: 'blue'
}

Answer 1

You're just testing the first value, not all of them.

function hasOnlyStrings(o) {
    for (var val in o) {
        var values = o[match];
        if (typeof values != 'string') {
            return false;
        } 
    }
    return true;
}

Answer 2

I think you need

function hasOnlyStrings(o) {
    for (var prop in o)
        if (typeof o[prop] !== 'string')
            return false;
    return true;
}

Also consider using o.hasOwnProperty(prop) if you want to avoid checking properties inherited from prototype.