Obtaining a String from a Nested Array through Nested Iterations

Question

Obtaining a String from a Nested Array through Nested Iterations

As someone who is just starting out with coding, I am currently focused on practicing loops and arrays. One of my exercises involves working with an array that contains multiple sub arrays, each of them consisting of pairs of strings. My goal is to extract and isolate each individual string using a set of nested for loops.

const pairs = [['Blue', 'Green'],['Red', 'Orange'],['Pink', 'Purple']];

//Using nested arrays to access each string from the array 
function getString(arr){
    //First loop to iterate through the list of arrays
    for (let i = 0; i < arr.length; i++){
        console.log(i , arr[i]);
        //Assigning each sub array to a new variable for iteration
        subArr = arr[i];
    } 
    //Second loop to get each string from the sub arrays
    for (let j = 0; j < subArr.length; j++){
        console.log(j, arr[j]);
    }
};


console.log(getString(pairs));

The issue I am facing is that the output of the last loop is showing ['Pink', 'Purple'] as a whole, rather than each individual color extracted from the nested loops.

Can anyone point out where I might be going wrong in my approach?

Mirii

javascript arrays nested-for-loop

Answer 1

Answer №1

Your loops are not nested properly: the first loop is being closed before the second one begins. The variable subArr is a global variable (not defined using let, const, or var), which means it is still accessible in the second loop. However, this is not the recommended way to structure your code. Additionally, you should be logging arr[i][j] instead of what you currently have.

Here is the corrected version:

function getString(arr) {
  // Loop through the list of arrays
  for (let i = 0; i < arr.length; i++){
    // Assign each subarray to a new variable for iteration
    let subArr = arr[i];
    for (let j = 0; j < subArr.length; j++){
      console.log(arr[i][j]);
    }
  }
};
getString(pairs);

Another issue is that you are calling console.log(getString(pairs)), but getString does not return anything, it just logs the output. If you want it to return a newline-delimited string of all the items, you could push the items to an array and return them joined with a newline character:

function getString(arr) {
  let ret = []
  // Loop through the list of arrays
  for (let i = 0; i < arr.length; i++){
    // Assign each subarray to a new variable for iteration
    let subArr = arr[i];
    for (let j = 0; j < subArr.length; j++){
      ret.push(arr[i][j]);
    }
  }
  return ret.join('\n')
};

console.log(getString(pairs));

Nesting loops is not the most readable method, using array methods such as forEach is more concise:

function getString (arr) {
  arr.forEach(function (subArr) {
    console.log(subArr[0])
    console.log(subArr[1])
  })
}

getString(pairs)

Alternatively, you can use map for a more succinct solution:

function getString (arr) {
  return arr.map(([ a, b ]) => `${a}\n${b}`).join('\n');
}
console.log(getString(pairs))

For an even more concise approach, you can utilize [].flat():

const getString = (xs = []) => xs.flat().join('\n')
console.log(getString(pairs))

Answer 2

Your loops are not nested properly: the first loop is being closed before the second one begins. The variable subArr is a global variable (not defined using let, const, or var), which means it is still accessible in the second loop. However, this is not the recommended way to structure your code. Additionally, you should be logging arr[i][j] instead of what you currently have.

Here is the corrected version:

function getString(arr) {
  // Loop through the list of arrays
  for (let i = 0; i < arr.length; i++){
    // Assign each subarray to a new variable for iteration
    let subArr = arr[i];
    for (let j = 0; j < subArr.length; j++){
      console.log(arr[i][j]);
    }
  }
};
getString(pairs);

Another issue is that you are calling console.log(getString(pairs)), but getString does not return anything, it just logs the output. If you want it to return a newline-delimited string of all the items, you could push the items to an array and return them joined with a newline character:

function getString(arr) {
  let ret = []
  // Loop through the list of arrays
  for (let i = 0; i < arr.length; i++){
    // Assign each subarray to a new variable for iteration
    let subArr = arr[i];
    for (let j = 0; j < subArr.length; j++){
      ret.push(arr[i][j]);
    }
  }
  return ret.join('\n')
};

console.log(getString(pairs));

Nesting loops is not the most readable method, using array methods such as forEach is more concise:

function getString (arr) {
  arr.forEach(function (subArr) {
    console.log(subArr[0])
    console.log(subArr[1])
  })
}

getString(pairs)

Alternatively, you can use map for a more succinct solution:

function getString (arr) {
  return arr.map(([ a, b ]) => `${a}\n${b}`).join('\n');
}
console.log(getString(pairs))

For an even more concise approach, you can utilize [].flat():

const getString = (xs = []) => xs.flat().join('\n')
console.log(getString(pairs))

Answer 3

Answer №2

The optimal way to structure the for loops is by nesting them in this manner:

for (let i = 0; i < arr.length; i++) {
  console.log(i, arr[i]);
  //It is important to assign each sub array to a new variable for iteration
  subArr = arr[i];

  for (let j = 0; j < subArr.length; j++) {
    console.log(j, arr[j]);
  }
}

If arranged differently, they would execute sequentially rather than concurrently.

Answer 4

The optimal way to structure the for loops is by nesting them in this manner:

for (let i = 0; i < arr.length; i++) {
  console.log(i, arr[i]);
  //It is important to assign each sub array to a new variable for iteration
  subArr = arr[i];

  for (let j = 0; j < subArr.length; j++) {
    console.log(j, arr[j]);
  }
}

If arranged differently, they would execute sequentially rather than concurrently.

Answer 5

Answer №3

The answer has been given:

function extractString(arr) {
  let resultArray = [];

  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr[i].length; j++) {
      resultArray.push(arr[i][j]);
    }
  }

  return resultArray;
}

Answer 6

The answer has been given:

function extractString(arr) {
  let resultArray = [];

  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr[i].length; j++) {
      resultArray.push(arr[i][j]);
    }
  }

  return resultArray;
}

Answer 7

Answer №4

To effectively navigate through nested arrays, it is important to nest your loops accordingly. Using the .forEach method can simplify your code and provide a clearer structure.

For instance, you can iterate through pairs and then through subpairs within each pair, like so:

pairs.forEach((pair, i) => {
  pair.forEach((subPair, j) => {
    console.log(j, subPair);
  });
});

Alternatively, you can create a variable, populate it within the pair.forEach loop, and return it at the end of your main function for further processing.

I trust this explanation resolves your query. Thank you for reaching out and have a wonderful day!

Answer 8

To effectively navigate through nested arrays, it is important to nest your loops accordingly. Using the .forEach method can simplify your code and provide a clearer structure.

For instance, you can iterate through pairs and then through subpairs within each pair, like so:

pairs.forEach((pair, i) => {
  pair.forEach((subPair, j) => {
    console.log(j, subPair);
  });
});

Alternatively, you can create a variable, populate it within the pair.forEach loop, and return it at the end of your main function for further processing.

I trust this explanation resolves your query. Thank you for reaching out and have a wonderful day!

Obtaining a String from a Nested Array through Nested Iterations

Answer №1

Answer №2

Answer №3

Answer №4

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