Get values from an object (with arrays) using a string

Question

I found this code (https://stackoverflow.com/a/8817473/1778465), which works nicely, but when I want to get a value from an array such as item 1 I get undefined, I am not really sure what I can do to get array items as well. Any ideas?

This is the code:

var obj = {
    foo: { bar: {animals: [{name: "Billy"},{name: "Bob"},{name: "Joe"}]}}
};

var deep_value = function(obj, path){
    for (var i=0, path=path.split('.'), len=path.length; i<len; i++){
        obj = obj[path[i]];
    };
    return obj;
};

console.log(deep_value(obj, 'foo.bar.animals[1].name'));  // Should show "Bob"

The above gives me the following error:

Uncaught TypeError: Cannot read property 'name' of undefined

Fiddle Found Here

Tuan Anh Hoang-Vu · Accepted Answer · 2015-07-09 17:46:05Z

2

You're almost there. This code will give you what you want:

console.log(deep_value(obj, 'foo.bar.animals.1.name'));  // Should show "Bob"

Edit: If you still want to use the [1] syntax for array, here is an alternative version (split the path by ., [ and ]:

var obj = {
    foo: { bar: {animals: [{name: "Billy"},{name: "Bob"},{name: "Joe"}]}}
};

var deep_value = function(obj, path){
    for (var i=0, path=path.split(/[\[\]\.]/), len=path.length; i<len; i++){
        if (path[i]){
            obj = obj[path[i]];
        }
    };
    return obj;
};

console.log(deep_value(obj, 'foo.bar.animals[1].name'));  // Should show "Bob"

edited Jul 9, 2015 at 17:46

answered Jul 9, 2015 at 17:38

Tuan Anh Hoang-Vu

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3 Comments

Get Off My Lawn Over a year ago

never thought of that... I do like the [1] version though because then we know that it is an array... Is it at all possible for that syntax?

Brent Echols Over a year ago

you could extend the language to also parse an array index, and simply use a regex to match [^[[]+]. That way you can pull out what you are indexing, and simply go about your business the same way as before.

Get Off My Lawn Over a year ago

That is awesome! works like a charm, and supports deep arrays! This works too: foo.bar.animals[0].colors[1]. Thank you very much!

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