What is the best way to retrieve all the names stored within a nested object?

Question

What is the best way to retrieve all the names stored within a nested object?

I am currently delving into the realm of JavaScript and my instructor has given me an exercise to create a function that will output an array containing all the names from the nested object below:

{
  name: 'grandma',
  daughter: {
    name: 'mother',
    daughter: {
      name: 'daughter',
      daughter: {
        name: 'granddaughter'
      }
    }
  }
}

My predicament is akin to a query posted on Stack Overflow, but the provided solution does not quite fit my scenario as my object structure lacks arrays. The code snippet I have managed to put together thus far looks like this:

    function convertToArray(obj) {
  const result = [];
    for (const prop in obj) {
        const value = obj[prop];
        if (typeof value === 'object') {
            result.push(convertToArray(value));
        }
        else {
            result.push(value);
        }
    }
    return result;
}

function extractNames(target) {

return convertToArray(target);

}

The output currently reads:

[ 'grandma', [ 'mother', [ 'daughter', [Array] ] ] ]

However, my instructor's expectations are aligned with:

['grandma', 'mother', 'daughter', 'granddaughter']

Access the codepen here

javascript

Answer 1

Answer №1

It is clear that the task involves pushing an array into another array, where all nested children are treated as separate elements in the array.

To address this issue, one approach is to iterate through the array and only add individual items to the final result set.

Alternatively, you can utilize certain built-in methods designed to work with arrays and flatten them into a single array without any nesting.

Here are some methods:

Array#concat, which creates a new array and is compatible with older versions of JavaScript.
```
result = result.concat(toArray(value));
```
Array#push along with an array and Function#apply for accepting an array as parameter list. This method works directly on the original array and is compatible with older JS versions.
```
Array.prototype.push.apply(result, toArray(value));
[].push.apply(result, toArray(value));              // requires an additional empty array
```
Spread syntax ... for expanding an array into parameters. ES6
```
result.push(...toArray(value));
```
Spread syntax is a robust alternative to apply with broader applicability. Check out the examples for more clarity.

An example showcasing the use of spread syntax.

 function toArray(obj) {
    const result = [];
    for (const prop in obj) {
        const value = obj[prop];
        if (value && typeof value === 'object') { // exclude null
            result.push(...toArray(value));
            //          ^^^                          spread the array
        }
        else {
            result.push(value);
        }
    }
    return result;
}

function nameMatrioska(target) {
    return toArray(target);
}

var object = { name: 'grandma', daughter: { name: 'mother', daughter: { name: 'daughter', daughter: { name: 'granddaughter' } } } };

console.log(nameMatrioska(object));

Answer 2

It is clear that the task involves pushing an array into another array, where all nested children are treated as separate elements in the array.

To address this issue, one approach is to iterate through the array and only add individual items to the final result set.

Alternatively, you can utilize certain built-in methods designed to work with arrays and flatten them into a single array without any nesting.

Here are some methods:

Array#concat, which creates a new array and is compatible with older versions of JavaScript.
```
result = result.concat(toArray(value));
```
Array#push along with an array and Function#apply for accepting an array as parameter list. This method works directly on the original array and is compatible with older JS versions.
```
Array.prototype.push.apply(result, toArray(value));
[].push.apply(result, toArray(value));              // requires an additional empty array
```
Spread syntax ... for expanding an array into parameters. ES6
```
result.push(...toArray(value));
```
Spread syntax is a robust alternative to apply with broader applicability. Check out the examples for more clarity.

An example showcasing the use of spread syntax.

 function toArray(obj) {
    const result = [];
    for (const prop in obj) {
        const value = obj[prop];
        if (value && typeof value === 'object') { // exclude null
            result.push(...toArray(value));
            //          ^^^                          spread the array
        }
        else {
            result.push(value);
        }
    }
    return result;
}

function nameMatrioska(target) {
    return toArray(target);
}

var object = { name: 'grandma', daughter: { name: 'mother', daughter: { name: 'daughter', daughter: { name: 'granddaughter' } } } };

console.log(nameMatrioska(object));

Answer 3

Answer №2

It's important to use .concat instead of .push. Push adds a single item to an array, while concat combines two arrays together.

['grandmother'].concat(['mother', 'daughter'])
-> ['grandmother', 'mother', 'daughter']

Unlike the push method which alters the original array, the concat method creates a new array.

var a1 = [ 'grandmother' ];
a1.push( 'mother' );
console.log( a1 );
-> ['grandmother', 'mother']

var a2 = [ 'steve' ];
var result = a2.concat(['Jesus', 'Pedro']);
console.log( a1 );
-> ['steve']
console.log( result );
-> ['steve', 'Jesus', 'Pedro']

Answer 4

It's important to use .concat instead of .push. Push adds a single item to an array, while concat combines two arrays together.

['grandmother'].concat(['mother', 'daughter'])
-> ['grandmother', 'mother', 'daughter']

Unlike the push method which alters the original array, the concat method creates a new array.

var a1 = [ 'grandmother' ];
a1.push( 'mother' );
console.log( a1 );
-> ['grandmother', 'mother']

var a2 = [ 'steve' ];
var result = a2.concat(['Jesus', 'Pedro']);
console.log( a1 );
-> ['steve']
console.log( result );
-> ['steve', 'Jesus', 'Pedro']

Answer 5

Answer №3

Give this a try

function convertToArray(obj) {
  var output = "";
    for (const property in obj) {
        const data = obj[property];
        if (typeof data === 'object') {
            output = output.concat(" " + convertToArray(data));
        }
        else {
            output = output.concat(data);
        }
    }

    return output; 
}

function extractWords(input) {

return convertToArray(input).split(" ");

}

Answer 6

Give this a try

function convertToArray(obj) {
  var output = "";
    for (const property in obj) {
        const data = obj[property];
        if (typeof data === 'object') {
            output = output.concat(" " + convertToArray(data));
        }
        else {
            output = output.concat(data);
        }
    }

    return output; 
}

function extractWords(input) {

return convertToArray(input).split(" ");

}

Answer 7

Answer №4

function convertToArray(obj) {
  var resultArr = [];

  for (var property in obj) {
    var value = obj[property];
    if (typeof value === 'object') {
      resultArr = resultArr.concat(convertToArray(value))
    } else {
      resultArr.push(value);
    }
  }
  return resultArr;
}

function extractNames(targetObj) {
  return convertToArray(targetObj);
}

//CUSTOM
var familyNames = {
  name: 'grandma',
  daughter: {
    name: 'mother',
    daughter: {
      name: 'daughter',
      daughter: {
        name: 'granddaughter'
      }
    }
  }
};

console.log(extractNames(familyNames));
//Output: ["grandma", "mother", "daughter", "granddaughter"]

Answer 8

function convertToArray(obj) {
  var resultArr = [];

  for (var property in obj) {
    var value = obj[property];
    if (typeof value === 'object') {
      resultArr = resultArr.concat(convertToArray(value))
    } else {
      resultArr.push(value);
    }
  }
  return resultArr;
}

function extractNames(targetObj) {
  return convertToArray(targetObj);
}

//CUSTOM
var familyNames = {
  name: 'grandma',
  daughter: {
    name: 'mother',
    daughter: {
      name: 'daughter',
      daughter: {
        name: 'granddaughter'
      }
    }
  }
};

console.log(extractNames(familyNames));
//Output: ["grandma", "mother", "daughter", "granddaughter"]

Answer 9

Answer №5

You are very close to finding the solution.
Remember to flatten your array in the final step.
A helpful tip: Always be cautious when checking for object types as JavaScript considers null and undefined as objects too!

function isObject(value) {
  if(value === undefined) return "Undefined";
  if(value === null) return "Null";
  const string = Object.prototype.toString.call(value);
  return string.slice(8, -1);
}

function collectPropertiesRec(object, propertyName) {
  const result = [ ];
  for(const currentPropertyName in object) {
    const value = object[currentPropertyName];
    if(isObject(value) === 'Object') {
        result.push(collectPropertiesRec(value, propertyName));
    }
    else if(currentPropertyName === propertyName) {
      result.push(value);
    }
  }
  return result;
}

function flattenDeep(arr1) {
    return arr1.reduce((acc, val) => Array.isArray(val) ? acc.concat(flattenDeep(val)) : acc.concat(val), [ ]);
  }

//USER
const names =  {
  name: 'grandma',
  daughter: {
    name: 'mother',
    daughter: {
      name: 'daughter',
      daughter: {
        name: 'granddaughter'
      }
    }
  }
};

var result = collectPropertiesRec(names, "name");
alert(flattenDeep(result).join(", "));

Answer 10

You are very close to finding the solution.
Remember to flatten your array in the final step.
A helpful tip: Always be cautious when checking for object types as JavaScript considers null and undefined as objects too!

function isObject(value) {
  if(value === undefined) return "Undefined";
  if(value === null) return "Null";
  const string = Object.prototype.toString.call(value);
  return string.slice(8, -1);
}

function collectPropertiesRec(object, propertyName) {
  const result = [ ];
  for(const currentPropertyName in object) {
    const value = object[currentPropertyName];
    if(isObject(value) === 'Object') {
        result.push(collectPropertiesRec(value, propertyName));
    }
    else if(currentPropertyName === propertyName) {
      result.push(value);
    }
  }
  return result;
}

function flattenDeep(arr1) {
    return arr1.reduce((acc, val) => Array.isArray(val) ? acc.concat(flattenDeep(val)) : acc.concat(val), [ ]);
  }

//USER
const names =  {
  name: 'grandma',
  daughter: {
    name: 'mother',
    daughter: {
      name: 'daughter',
      daughter: {
        name: 'granddaughter'
      }
    }
  }
};

var result = collectPropertiesRec(names, "name");
alert(flattenDeep(result).join(", "));

What is the best way to retrieve all the names stored within a nested object?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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