Javascript For...In syntax issue?

Question

The search function in the following code is not working and I believe it has something to do with the For...In loop but I am new to JS and unsure why:

var friends = {
bill: {
    firstName: "bill",
    lastName: "smith",
    number: 1,
    address: ["1"]
},
steve: {
    firstName: "steve",
    lastName: "smith",
    number: 2,
    address: ["2"]
}
};

var list = function(list) {
for(var item in list) {
    console.log(item);
}
};

var search = function(name) {

for(var friend in friends) {
    if(friend.firstName === name) {
        console.log(friend);
        return friend;
    }
}
};

search("steve");

I recommend to refer to the MDN documentation if you are unsure about a certain function or construct: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…. — Felix Kling
– Felix Kling, Commented Aug 26, 2013 at 20:04

SLaks · Accepted Answer · 2013-08-26 20:00:38Z

2

The for in loop iterates over keys, not values.

friend is a string holding the name of each property.
To get the value, use friends[friend].

answered Aug 26, 2013 at 20:00

SLaks

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Chase · Accepted Answer · 2013-08-26 20:22:33Z

0

Great documentation of the for..in loop can be found on mdn. Where variable is assigned through each iteration to "a different property name".

You also may not need to loop through each friend. What if you changed your search function to use hasOwnProperty on the object:

var search = function(name) {
    if(friends.hasOwnProperty(name)){
        return friends[name];
    }
};

This would check that you have a property of name in the object friends and return it. Here's a quick EXAMPLE.

edited Aug 26, 2013 at 20:22

answered Aug 26, 2013 at 20:14

Chase

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