Replace value while iterating through nested json file in javascript

Question

I've searched for a long time, but cannot find any solution for my problem... I got a random nested json object like this:

var obj = { a: 1, b: 2, c: { a: 1, b: 2, c: {a: 'hello', b: 'HowAreYou?'} } };
someValue = 'hello';
newValue = 'bye';

Now I'm going to search for 'someValue'. If 'obj' contains this value the alert will be triggered. Here's my example:

function wannaChangeValue(obj) {
    var itemKey;
    if (obj instanceof Object) {
        for (itemKey in obj) {
            if (obj.hasOwnProperty(itemKey)) {
                wannaChangeValue(obj[itemKey]);
            }
        }
    } else {
        alert(obj);
        if (obj == someValue) {
            alert('got it! now change...')
            //change someValue to newValue 
        }
    }
    return obj
}

wannaChangeValue(obj)

This works really fine, but how can I change 'someValue' to 'newValue' and return the whole json-file again? I've seen many examples how to handle this, but I need a solution for ANY kind of nested json object WITHOUT knowing the path for changing this value. Maybe this is a completely wrong approach... Thanks in advance!

Possible duplicate of Find and update in nested json object. Another link that might help: stackoverflow.com/questions/15523514/… — Rajesh Dixit
– Rajesh Dixit, Commented Aug 3, 2017 at 9:58

Nina Scholz · Accepted Answer · 2017-08-03 10:01:02Z

4

You could use a recursice approach for any found object, call the function again.

function update(object, search, replace) {
    Object.keys(object).forEach(function (k) {
        if (object[k] && typeof object[k] === 'object') {
            return update(object[k], search, replace)
        }
        if (object[k] === search) {
            object[k] = replace;
        }
    });
    
}

var object = { a: 1, b: 2, c: { a: 1, b: 2, c: {a: 'hello', b: 'HowAreYou?'} } };
    
update(object, 'hello', 'bye');

console.log(object)

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answered Aug 3, 2017 at 10:01

Nina Scholz

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8 Comments

Rajesh Dixit Over a year ago

What is the purpose of this: object[k] &&?

Nina Scholz Over a year ago

it prevents null values to gets iterated by keys.

Rajesh Dixit Over a year ago

I think, my comment on @Alexandru-Ionut Mihai's answer would not only solve your usecase, but will also optimize as there should be no need to traverse node tree that does not have the key

Nina Scholz Over a year ago

hm. yes and no. yes, because it shortens the iteration and no, because of the overhead for every nested object.

Nina Scholz Over a year ago

@HassanImam, it prevents the next if clause to be evaluated.

|

Nenad Vracar · Accepted Answer · 2017-08-03 09:53:43Z

2

You can create function using for...in loop and if current value match oldValue change that value.

var obj = { a: 1, b: 2, c: { a: '1', b: 2, c: {a: 'hello', b: 'HowAreYou?'} } };
var someValue = 'hello';
var newValue = 'bye';

function changeVal(data, oldV, newV) {
  for(var i in data) {
    if(typeof data[i] == 'object') changeVal(data[i], oldV, newV);
    if(data[i] == oldV) data[i] = newV
  }
  return data
}

console.log(changeVal(obj, someValue, newValue))

answered Aug 3, 2017 at 9:53

Nenad Vracar

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Comments

Mihai Alexandru-Ionut · Accepted Answer · 2017-08-03 09:58:00Z

0

You can define a function which search recursively the value through your object and then replace this value.

function replaceObj (obj, valueForSearch,valueForReplace) {
    for (var key in obj) {
        var value = obj[key];
        if (typeof value === 'object') {
            replaceObj(value, valueForSearch,valueForReplace);
        }
        if (value === valueForSearch) {
            obj[key]=valueForReplace;
        }
    }
}
let obj = { a: 1, b: 2, c: { a: 1, b: 2, c: {a: 'hello', b: 'HowAreYou?'} } };
let someValue = 'hello';
let newValue = 'bye';
replaceObj(obj,someValue,newValue);
console.log(obj);

edited Aug 3, 2017 at 9:58

answered Aug 3, 2017 at 9:52

Mihai Alexandru-Ionut

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1 Comment

Rajesh Dixit Over a year ago

You can even optimize it as typeof value === 'object' && JSON.stringify(value).indexOf(query)>=0

Matthew Lewis · Accepted Answer · 2017-08-03 09:59:38Z

0

This is a quick solution:

function wannaChangeValue(obj) {
    var itemKey;
    if (obj instanceof Object) {
        for (itemKey in obj) {
            if (obj.hasOwnProperty(itemKey)) {
                obj[itemKey] = wannaChangeValue(obj[itemKey]);
            }
        }
    } else {
        alert(obj);
        if (obj == someValue) {
            alert('got it! now change...')
            //change someValue to newValue
            obj = someValue;
        }
    }
    return obj
}

wannaChangeValue(obj)

Obviously this will mutate the value on the object itself, so if you want an entirely new object you will have to do something different.

answered Aug 3, 2017 at 9:59

Matthew Lewis

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Comments

Narendra Jadhav · Accepted Answer · 2018-11-01 05:51:03Z

0

You could use recursive call for your object.

Demo

var object = { a: 1, b: 2, c: { a: '1', b: 2, c: {a: 'hello', b: 'HowAreYou?'} } },
  someValue = 'hello',
  newValue = 'bye';

function wannaChangeValue(obj) {
  var itemKey;
  if (obj instanceof Object) {
    for (itemKey in obj) {
      if (obj.hasOwnProperty(itemKey)) {
        if (!(obj[itemKey] instanceof Object) && obj[itemKey] == someValue) {
          //alert(someValue + ' got it! now change...')
          //change someValue to newValue
          obj[itemKey] = newValue;
          break;
        } else {
          wannaChangeValue(obj[itemKey]);
        }
      }
    }
  }
}
wannaChangeValue(object);
console.log(object)

.as-console-wrapper {max-height: 100% !important;top: 0;}

edited Nov 1, 2018 at 5:51

answered Aug 3, 2017 at 10:04

Narendra Jadhav

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1 Comment

Rajesh Dixit Over a year ago

Dude you have to just need to some change your code like below code it will work for you. This is a comment line, which would be flagged as Too Chatty. An answer should have an Explanation.

vincent · Accepted Answer · 2021-01-07 01:01:01Z

0

Here is a solution using object-scan

// const objectScan = require('object-scan');

const obj = { a: 1, b: 2, c: { a: 1, b: 2, c: { a: 'hello', b: 'HowAreYou?' } } };

const replace = (input, oldValue, newValue) => objectScan(['**'], {
  abort: true,
  rtn: 'bool',
  filterFn: ({ value, parent, property }) => {
    if (value === oldValue) {
      parent[property] = newValue;
      return true;
    }
    return false;
  }
})(input);

console.log(replace(obj, 'hello', 'bye')); // returns true iff replace happened
// => true
console.log(obj);
// => { a: 1, b: 2, c: { a: 1, b: 2, c: { a: 'bye', b: 'HowAreYou?' } } }

.as-console-wrapper {max-height: 100% !important; top: 0}

<script src="https://bundle.run/[email protected]"></script>

Disclaimer: I'm the author of object-scan

edited Jan 7, 2021 at 1:01

answered Dec 27, 2020 at 6:12

vincent

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