finding property in js object by name

Question

I've got many objects that structures aren't the same. But I know that all of them have got property name 'siteName'. My question is how can I get value from this property. Explame of few objects:

feature1 = {
    display: "name",
    feature: {
        attributes: {
            when: '111',
            what: '222'
        },
        geometry: null
        infoTemplate: undefined
    },
    symbol: null
    siteName: 'aa'
}

feature2 = {
    feature: {
        attributes: {
            when: '111',
            what: '222'
        },
        geometry: null
        infoTemplate: undefined
    },
    static: {
        format: {
            weight: 12,
            siteName: 'cccc'
        },
    }
}

possible duplicate of [Dynamic object property name](http://stackoverflow.com/questions/4244896/dynamic-object-property-name) — Esailija, Dec 03 '12 at 14:00
@Esailija: I don't think that's a dupe. I think the point is that the location of the property in the nested structure is not predictable. — I Hate Lazy, Dec 03 '12 at 14:01
@Esailija it isn't duplicate - I want to find property in object by name — Krystian, Dec 03 '12 at 14:02
i think i should iterate trought the object - to find this property, but I dont know how to do it. — Krystian, Dec 03 '12 at 14:04

I Hate Lazy · Accepted Answer · 2012-12-03T14:17:03.050

3

Here's a recursive function that should work for you.

It returns the value of the first property found with the name, otherwise returns undefined.

function findByName(obj, prop) {
    for (var p in obj) {
        if (p === prop) {
            return obj[p];
        } else if (obj[p] && typeof obj[p] === "object") {
            var result = findByName(obj[p], prop);
            if (result !== undefined)
                return result;
        }
    }
}

var result = findByName(myObject, "siteName");

Or here's another variation that avoids inherited properties.

function findByName(obj, prop) {
    if (obj.hasOwnProperty(prop))
        return obj[prop];

    for (var p in obj) {
        if (obj[p] && typeof obj[p] === "object") {
            var result = findByName(obj[p], prop);
            if (result !== undefined)
                return result;
        }
    }
}

edited Dec 03 '12 at 14:17

answered Dec 03 '12 at 14:08

I Hate Lazy

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Oh the cruel world of Stackoverflow. Beaten you to a answer by 8 seconds, but too slow to properly implement the recursiveness... Well played. – Cerbrus Dec 03 '12 at 14:26
Beautiful function. I think I might have to use this later...and cerbrus...I was just working on the same thing when I found out he had posted this already...sucks to be on a laptop keyboard. – SomeShinyObject Dec 03 '12 at 14:29
@Cerbrus: Yeah I saw your answer there... figured you'd have it updated pretty soon since you were so close. But FWIW, you don't need the `toLowerCase()`. You'll always get a lowercase `"object"` from `typeof` for native objects. :) – I Hate Lazy Dec 03 '12 at 14:31
That was exactly the thing that was costing me time. For some reason, I typed `typeof obj[k] == "Object"`, and that took me too long to debug :-/ @Christopher: shall we upvote each other so we can try to compete with a accepted answer? :P – Cerbrus Dec 03 '12 at 14:34
@Cerbrus, I never even finished getting the answer complete. Maybe next time I'll type faster. – SomeShinyObject Dec 05 '12 at 00:32

Cerbrus · Answer 2 · 2012-12-03T14:41:06.337

Recursively loop through the objects:

function find(obj, name) {
    for (var k in obj) { // Loop through all properties of the object.
        if(k == name){ // If the property is the one you're looking for.
            return obj[k]; // Return it.
        }else if (typeof obj[k] == "object"){ // Else, if the object at [key] is a object,
            var t = find(obj[k], name); // Loop through it.
            if(t){ // If the recursive function did return something.
                return t; // Return it to the higher recursion iteration, or to the first function call.
            }
        }               
    }
}

Usage:

find(feature1, "siteName"); //Returns "aa"

score 0 · Answer 3 · answered Dec 03 '12 at 14:15

The following function should suit your needs:

function getFirstFoundPropertyValue(searchedKey, object) {
    if(typeof object === "object") {
        for (var key in object) {
            var currentValue = object[key];
            if(key === searchedKey) {
                return currentValue;
            }
            var nested = getFirstFoundPropertyValue(searchedKey, currentValue);
            if(typeof nested !== "undefined") {
                return nested;
            }
        }
    }
}

It returns the value of the key if the key is found, undefined otherwise. If the key appears several times, the first found one will be returned.

finding property in js object by name

3 Answers3