Transforming a list into an array using JavaScript

Question

Transforming a list into an array using JavaScript

This specific function serves to convert a list into an array:

const myList = {"value":10,"rest":{"value":20,"rest":null}};

function convertListToArray(list) {
  let arr = [];
  for (const prop in list) {
    if (prop == "value") {
      arr.push(prop);
    } else if (prop == "rest") {
      for (const innerProp in rest) {
        arr.push(innerProp);
      }
    }
  }
}
console.log(JSON.stringify(convertListToArray(myList)));

However, encountering the error

Uncaught ReferenceError ReferenceError: rest is not defined

What is the best way to iterate through the rest object? Or can you propose an alternative approach to rewrite this function?

javascript arrays list

Answer 1

Answer №1

To implement this, it is necessary to utilize recursion specifically for the "rest" property. To access the value, make use of list[property]:

function list_to_array(list) {
  const arr = [];
  
  for (const property in list) {
    if (property == "value") {
      arr.push(list[property]);
    } else if (property == "rest") {
      arr.push(...list_to_array(list[property])); // execute list_to_array recursively on the rest
    }
  }
  
  return arr; // return the array
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

Alternatively, you can simplify the recursive process by consistently adding the value. If there is a "rest" property present, call the function with the "rest" and the current array "arr". If no "rest" exists, simply return "arr":

function list_to_array({ value, rest } = {}, arr = []) {
  arr.push(value);
  return rest ? list_to_array(rest, arr) : arr;
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

An easier approach would involve utilizing a "while" loop to extract the value of the "rest" property during each iteration:

function list_to_array(list) {
  const arr = [];
  let current = list;
  
  do {
    arr.push(current?.value);
  } while(current = current?.rest);
  
  return arr; // return the array
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

Answer 2

To implement this, it is necessary to utilize recursion specifically for the "rest" property. To access the value, make use of list[property]:

function list_to_array(list) {
  const arr = [];
  
  for (const property in list) {
    if (property == "value") {
      arr.push(list[property]);
    } else if (property == "rest") {
      arr.push(...list_to_array(list[property])); // execute list_to_array recursively on the rest
    }
  }
  
  return arr; // return the array
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

Alternatively, you can simplify the recursive process by consistently adding the value. If there is a "rest" property present, call the function with the "rest" and the current array "arr". If no "rest" exists, simply return "arr":

function list_to_array({ value, rest } = {}, arr = []) {
  arr.push(value);
  return rest ? list_to_array(rest, arr) : arr;
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

An easier approach would involve utilizing a "while" loop to extract the value of the "rest" property during each iteration:

function list_to_array(list) {
  const arr = [];
  let current = list;
  
  do {
    arr.push(current?.value);
  } while(current = current?.rest);
  
  return arr; // return the array
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = list_to_array(list);

console.log(JSON.stringify(result));

Answer 3

Answer №2

It is advisable to steer clear of using recursion in this case, especially when dealing with large lists as it may easily cause a stack overflow. A straightforward while loop would be more suitable:

function convert_list_to_array(list) {
  const arr = [list.value];
  while(list = list.rest) arr.push(list.value);
  return arr;
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = convert_list_to_array(list);

console.log(...result);

Answer 4

It is advisable to steer clear of using recursion in this case, especially when dealing with large lists as it may easily cause a stack overflow. A straightforward while loop would be more suitable:

function convert_list_to_array(list) {
  const arr = [list.value];
  while(list = list.rest) arr.push(list.value);
  return arr;
}

const list = {"value":10,"rest":{"value":20,"rest":null}};

const result = convert_list_to_array(list);

console.log(...result);

Answer 5

Answer №3

Here's a helpful tip: instead of using x = array_to_list([10, 20]);, you can use x = list_to_array([10, 20]); for better results.

Answer 6

Here's a helpful tip: instead of using x = array_to_list([10, 20]);, you can use x = list_to_array([10, 20]); for better results.

Transforming a list into an array using JavaScript

Answer №1

Answer №2

Answer №3

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