Question

I have a object

var foo = { jon : {age: 'old',   feeling: 'sad' },
            jack: {age: 'young', feeling: 'happy'}
          };

The members of foo are created dynamically; as is the object bar.

var bar = { name: 'jon' };

I would like to to see if jon is a member of foo. I must be doing something terribly wrong.

function isMember(bar) {
    for(prop in foo) {
        if (foo[prop] === bar.name){
            return true;
            break;
        }
    }
    return false;
};

always returns true!!

Answer 1

Here’s a working version of the above:

foo = { jon : {age: 'old',   feeling: 'sad' },
        jack: {age: 'young', feeling: 'happy'}
       };
bar = { name: 'jon' };

function isMember(bar) {
    for(prop in foo) {
        console.log([prop, foo[prop], bar.name, ]);
        if (prop === bar.name){
            return true;
        }
    }
    return false;
 };


console.log(['ismember', isMember(bar)]);

Live example:

• http://jsfiddle.net/BB4Tt/

Try changing bar.name to e.g. jon1 to see how it behaves. Take a look at your console window to see what it outputs, that will help you understanding what it does exactly and where you went wrong.

Hope this helps.