recursive function to search in json object in javascript

Question

I am trying to write a recursive function in javascript but not work properly. i have a json array of objects data where i want to find something based on key then find again based on gotopage key in search object.

like : find orange -> gotopage -> orange_store ->find -> orange_store -> gotopage -> yellow_store -> find so the same process goes in recursively.can you please help where i'm going wrong in my approach.

[
    {
        "id": 1,
        "find": "orange",
        "gotopage": "orange_store"
    },
    {
        "id": 2,
        "find": "orange_store",
        "gotopage": "yellow_store"
    },
    {
        "id": 3,
        "find": "black_store",
        "gotopage": "black_store"
    },
    {
        "id": 4,
        "find": "yellow_store",
        "gotopage": "white_store"
    },
    {
        "id": 5,
        "find": "black_store",
        "gotopage": "red_store"
    }
]


function searchRec(search, myArray) {
    for (var i = 0; i < myArray.length; i++) {
        var res = [];
        if (myArray[i].find == search) {
            if (myArray[i] !== null) {
                console.log(myArray[i]);
                res = searchRec(myArray[i].gotopage, myArray);
                if (res !== null) {
                    return res;
                }
                return myArray[i];
            }

        }
    }
}

function findNode(arr) {
    for (i = 0; i < arr.length; i++) {
        searchRec(arr[i].find, arr);
        break;
    }
}
console.log(findNode(json));

output for first iteration but not work for every iteration:

Object {id: 1, find: "orange", gotopage: "orange_store"}
Object {id: 2, find: "orange_store", gotopage: "yellow_store"}

You're checking for null returned from searchRec but never returning null. In javascript, indexing a missing element in an array will yield undefined not null. — ivo
– ivo, Commented Aug 24, 2017 at 15:35

Christopher Messer · Accepted Answer · 2017-08-24 15:40:21Z

2

Another example using recursion. I do a simple forEach() to find what you're looking for and store it in variables, log it, and re-call the function with our newly created values. If it doesn't find anything, it returns null and ends.

const data = [
    {
        "id": 1,
        "find": "orange",
        "gotopage": "orange_store"
    },
    {
        "id": 2,
        "find": "orange_store",
        "gotopage": "yellow_store"
    },
    {
        "id": 3,
        "find": "black_store",
        "gotopage": "black_store"
    },
    {
        "id": 4,
        "find": "yellow_store",
        "gotopage": "white_store"
    },
    {
        "id": 5,
        "find": "black_store",
        "gotopage": "red_store"
    }
];

function recursiveStore(search, myArray) {
    let obj = {}
    let newSearch;
    data.forEach(store => {
      if (search === store.find) {
        obj = store
        newSearch = store.gotopage 
      } 
    })
    if (Object.keys(obj).length === 0) {
        return null
    }
    console.log(obj)
    recursiveStore(newSearch, myArray)
}

recursiveStore("orange", data)

answered Aug 24, 2017 at 15:40

Christopher Messer

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4 Comments

truesource Over a year ago

thanks @christopher for best solution. i want to return obj instead of console.log ?

Christopher Messer Over a year ago

which object? all of them?

truesource Over a year ago

you wrote console.log(obj) after recursive function will call but what if i return instead of console.log.

Christopher Messer Over a year ago

if you wrote return instead - it would end there and not re-run itself. A function can only return one thing. You could do a couple of different things, like create an array outside of the object called stores and do something like stores.push(obj) instead of console.log(obj) and then still return recursiveStore(newSearch, myArray) and by the end, you'll have all the stores you need in one array of objects.

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