The value returned from the callback passed to forEach will not be used anywhere.

If you want to avoid mutating the original object and update questions, you can use Array.prototype.map and object spread syntax.

const object = {
  "id": "a8df1653-238a-4f23-fe42-345c5d928b34",
  "webSections": {
    "id": "x58654a9-283b-4fa6-8466-3f7534783f8",
    "sections": [
      {
        "id": "92d7e428-4a5b-4f7e-bc7d-b761ca018922",
        "title": "Websites",
        "questions": [
          { 
            id: 'dee6e3a6-f207-f3db-921e-32a0b745557', 
            ...

const updatedObject = {
 ...object,
 webSections: {
  ...object.webSections,
  sections: object.webSections.sections.map((section, index) => ({...section, questions: newMenu[index]}))
 }
}

If you just want to mutate the original object

object.webSections.sections.forEach((_, index) => {
 section.questions = newMenu[index]
})

You can use a nested map() to return a modified attributes array in the object.

let fruits = [{
    name: 'apple',
    attributes: [{
        type: 'Granny Smith',
        color: 'green',
        isFavorite: true
      },
      {
        type: 'Ambrosia',
        color: 'red',
        isFavorite: true
      }
    ],
    isFavorite: true
  },
  {
    name: 'Pear',
    attributes: [{
        type: 'Asian',
        color: 'brown',
        isFavorite: true
      },
      {
        type: 'White Pear',
        color: 'white',
        isFavorite: false
      }
    ],
    isFavorite: true
  },
]

const fruitChecked = fruits.map(fruit => ({ ...fruit,
  isFavorite: true,
  attributes: fruit.attributes.map(attribute => ({ ...attribute,
    isFavorite: true
  }))
}))

console.log(fruitChecked);

A little bit late to the party, heh. I needed to modify deeply nested objects too, and found no acceptable tool for that purpose. Then I've made this and pushed it to npm.

https://www.npmjs.com/package/find-and

This small lib can help with modifying nested objects in a lodash manner. E.g.,

var findAnd = require("find-and");

const obj_res =[{
  "id": "trans",
  "in": "bank",
  "out": "bank",
  "value": 10
 },{
 "id": "fund",
 "in": "bank",
 "out": "bank",
 "value": 10
}];

findAnd.changeProps(obj_res, { id: 'fund' }, { in: 'credit' });

outputs exactly what you want.

https://runkit.com/arfeo/find-and

Hope this could help someone else.

Inside the forEach, you are not really modifying the array. You are passing a value to forEach, corresponding to the values of the nested array. So when you change element's variable value, you are just changing it inside the forEach callback.

There are a few ways to do this... you can go something like this.

    let array = [
        ['A', '*', 'C'],
        ['A', 'B', 'C']
    ]
    
    for (let nestedArray of array) {
        if (nestedArray.includes('*')) {
            for (let i = 0; i < nestedArray.length; i++) nestedArray[i] = '*';
        }
    }
    
    console.log(array);

Or go by using splice if they all have the same fixed size (or even reassign the nestedArray to a ['*', '*', '*']).

Just to be clear: If you have this array: ['a', 'b', 'c']

And iterate it with forEach:

array.forEach(element => ...)

element will have the values 'a', 'b', 'c'. But those are NOT the same 'a', 'b', 'c' of the array. They are copies. So reassigning element to another value, won't affect the original array.

You used the wrong variable for the row index

myNumbers[column]
//needs to be
myNumbers[row]

Also your if condition is using the wrong row index, and trying to compare against the whole array instead of the value in the array

if(myNumbers[column]%2===0)
//needs to be
if(myNumbers[row][column]%2===0)

Demo

var myNumbers = [
  [243, 12, 23, 12, 45, 45, 78, 66, 223, 3],
  [34, 2, 1, 553, 23, 4, 66, 23, 4, 55],
  [67, 56, 45, 553, 44, 55, 5, 428, 452, 3],
  [12, 31, 55, 445, 79, 44, 674, 224, 4, 21],
  [4, 2, 3, 52, 13, 51, 44, 1, 67, 5],
  [5, 65, 4, 5, 5, 6, 5, 43, 23, 4424],
  [74, 532, 6, 7, 35, 17, 89, 43, 43, 66],
  [53, 6, 89, 10, 23, 52, 111, 44, 109, 80],
  [67, 6, 53, 537, 2, 168, 16, 2, 1, 8],
  [76, 7, 9, 6, 3, 73, 77, 100, 56, 100]
];

for (var row = 0; row < myNumbers.length; row++) {
  for (var column = 0; column < myNumbers[row].length; column++) {
    if (myNumbers[row][column] % 2 === 0) {
      myNumbers[row].splice(column, 1, "even");
    } else {
      myNumbers[row].splice(column, 1, "odd");
    }
  }
}
console.log(myNumbers);

reformat your data. it will be the best way moving forward.

  const array = [
    {
      car: 'ford',
      colour: 'red',
      food: {
          veg: 'beans',
          fruit: 'plum',
      },
    }
  ];

this way you can access the data like you want to food.fruit etc.

child property represents only one, but this alternative loops the whole array.

You can use recursion to go deeper and updated the found objects by id.

This approach mutates the original array

const allItems = [{  'id': 1,  'text': 'old',  'child': [    {      'id': 2,      'text': 'old'    }  ]}],
      newItems = [  {    'id': 1,    'text': 'new',    'more_info': 'abcd'  },  {    'id': 2,    'text': 'new',    'more_info': 'abcd'  }]
      looper = (arr, items) => {
        arr.forEach(outer => {
          let found = items.find(n => outer.id === n.id);
          if (found) {
            Object.assign(outer, found);
            if (outer.child) looper(outer.child, items);
          }
        });
      };

looper(allItems, newItems);
console.log(allItems);

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

You could iterate the array and replace the value inside.

var array = [{ _id: "ExxTDXJSwvRbLdtpg", content: [{ content: "First paragraph", language: "en", timestamp: 1483978498 }, { content: "Erster Abschnitt", language: "de", timestamp: 1483978498 }] }];

array.forEach(a => a.content = a.content.find(c => c.language === 'en').content);

console.log(array);

Version with check for content

var array = [{ _id: "ExxTDXJSwvRbLdtpg", content: [{ content: "First paragraph", language: "en", timestamp: 1483978498 }, { content: "Erster Abschnitt", language: "de", timestamp: 1483978498 }] }, { _id: "no_content" }, { _id: "no_english_translation", content: [{ content: "Premier lot", language: "fr", timestamp: 1483978498 }, { content: "Erster Abschnitt", language: "de", timestamp: 1483978498 }] }];

array.forEach(function (a) {
    var language;
    if (Array.isArray(a.content)) {
        language = a.content.find(c => c.language === 'en');
        if (language) {
            a.content = language.content;
        } else {
            delete a.content;
        }
    }
});

console.log(array);

Update the getAllKeys method with:

  function getAllKeys(o) {
    Object.keys(o).forEach(function(k) {
      contains_object = Array.isArray(o[k]) && o[k].some(val=> { return typeof val == "object" && !Array.isArray(val);  });
      if ((Array.isArray(o[k]) && !contains_object)  || typeof o[k] !== 'object') {
        keys[k] = o;
      } else {
        return getAllKeys(o[k]);
      }
      keys[k] = o;
    });
  }

Note: !(o[k] instanceof Array) - http://jsfiddle.net/08pnu7rx/1/

You can simply achieve that by iterating versions array :

const data = {
  versions: [{
    ver: 0,
    data: []
  }, {
    ver: 1,
    data: []
  }, {
    ver: 2,
    data: []
  }]
};

const replacedData = ['abc'];

data.versions.forEach(obj => {
    if (obj.ver === 1) {
    obj.data = replacedData
  }
});

console.log(data);