Issues arise when the Javascript splice function fails to properly combine array elements

Question

Issues arise when the Javascript splice function fails to properly combine array elements

My latest project involves developing a calculator application. The buttons in the HTML code add elements to an array, and when the user presses "=", the app is designed to iterate through the array. It combines numbers that are directly next to each other without any mathematical symbols between them. However, I encountered a challenge where I have to remove an element every time two numbers are successfully combined.

let equation = [1,2,3,"/",1,2,3];
combineNumbers();

function combineNumbers()//call to start finding solution by merging numbers
{
for(let i = 1; i < equation.length;i++)//iterates length of equation starting at 1
{
    if(isFinite(equation[i-1]) && isFinite(equation[i]))//checks if equation[i] and the index before it are numbers
    {
        equation[i-1] = '' + equation[i-1] + equation[i];//combines equation[i] and the index before
        equation.splice[i];//removes element at index i
    }
    else
    {
        i++;
    }

}
console.log(equation);
}

I experimented with iterating the length of the array backwards, but it only made things worse. Additionally, I tried various versions of the splice method, including

equation.splice[i]
equation.splice[i,1]

The current output using equation.splice[i] displays [12,23,3,"/",12,23,3], while the desired outcome should be [123,"/",123]

javascript arrays splice

Answer 1

Answer №1

You seem to be mixing up [ ] (index/property access) and ( ) (function call). The correct syntax should be equation.splice(i, 1).

Additionally, keep in mind that removing an item will cause the other indices to shift, which means you will skip one item unless you manually decrease your counter with i-- or iterate backwards instead of forwards.

_{On another note, it's unclear why you are intentionally skipping the next item in your else statement. Perhaps there shouldn't be any else at all?}

Answer 2

You seem to be mixing up [ ] (index/property access) and ( ) (function call). The correct syntax should be equation.splice(i, 1).

Additionally, keep in mind that removing an item will cause the other indices to shift, which means you will skip one item unless you manually decrease your counter with i-- or iterate backwards instead of forwards.

_{On another note, it's unclear why you are intentionally skipping the next item in your else statement. Perhaps there shouldn't be any else at all?}

Answer 3

Answer №2

By splicing the array and adjusting its length during iteration, it can lead to various complications. I opted for a different method where I gradually construct numbers and then add them to the result array once they are complete.

let equation = [1,2,"*",3,"/",1,2,3,"+",4];
combineNumbers();

function combineNumbers()//call to start finding solution by merging numbers
{
    let result = [];
  var currentNumberStr = "";
  for (var i = 0; i < equation.length; i++) {
    let symbol = equation[i];
    if (isFinite(symbol)) {
        currentNumberStr += symbol; // if symbol is a number, append to current number string
    } else {
        // Otherwise, we hit an operator. Push the current number str e.g. "123" and the operator to the result array
      result.push(currentNumberStr);
      result.push(symbol);
      // Reset the current number string
      currentNumberStr = "";
    }
  }
  // At the end, you have a currentNumberStr left over (the end 123). Push that
  result.push(currentNumberStr);
  
  console.log(result);
  
  return result;
}

Answer 4

By splicing the array and adjusting its length during iteration, it can lead to various complications. I opted for a different method where I gradually construct numbers and then add them to the result array once they are complete.

let equation = [1,2,"*",3,"/",1,2,3,"+",4];
combineNumbers();

function combineNumbers()//call to start finding solution by merging numbers
{
    let result = [];
  var currentNumberStr = "";
  for (var i = 0; i < equation.length; i++) {
    let symbol = equation[i];
    if (isFinite(symbol)) {
        currentNumberStr += symbol; // if symbol is a number, append to current number string
    } else {
        // Otherwise, we hit an operator. Push the current number str e.g. "123" and the operator to the result array
      result.push(currentNumberStr);
      result.push(symbol);
      // Reset the current number string
      currentNumberStr = "";
    }
  }
  // At the end, you have a currentNumberStr left over (the end 123). Push that
  result.push(currentNumberStr);
  
  console.log(result);
  
  return result;
}

Answer 5

Answer №3

Utilize

array.splice(index, deleteCount, ...items)

in order to swap out the elements within an array:
(and make use of i-- to loop again on the same index)
(and utilize unary plus (+) to convert to a number if converting to string by concatenating strings, I assume)

let equation = [1, 2, 3, "/", 1, 2, 3];
combineNumbers();

function combineNumbers() //call to begin the process of merging numbers
{
  for (let i = 1; i < equation.length; i++) //iterates over the length of the equation starting from 1
  {
    if (isFinite(equation[i - 1]) && isFinite(equation[i])) //checks if equation[i] and the index before it are both numbers
    {
      let text = '' + equation[i - 1] + equation[i]; //concatenates values at equation[i] and the previous index 
      equation.splice( /*start*/ i - 1, /*deleteCount*/ 2, /*...items*/ +text); //replace them with a numeric value
      i--; // repeat the same i
    }

  }
  console.log(equation);
}

Answer 6

Utilize

array.splice(index, deleteCount, ...items)

in order to swap out the elements within an array:
(and make use of i-- to loop again on the same index)
(and utilize unary plus (+) to convert to a number if converting to string by concatenating strings, I assume)

let equation = [1, 2, 3, "/", 1, 2, 3];
combineNumbers();

function combineNumbers() //call to begin the process of merging numbers
{
  for (let i = 1; i < equation.length; i++) //iterates over the length of the equation starting from 1
  {
    if (isFinite(equation[i - 1]) && isFinite(equation[i])) //checks if equation[i] and the index before it are both numbers
    {
      let text = '' + equation[i - 1] + equation[i]; //concatenates values at equation[i] and the previous index 
      equation.splice( /*start*/ i - 1, /*deleteCount*/ 2, /*...items*/ +text); //replace them with a numeric value
      i--; // repeat the same i
    }

  }
  console.log(equation);
}

Answer 7

Answer №4

This seems to be functioning properly, but there are a few issues that need to be addressed.

The check for determining if the equation is a number is incorrect.
The method equation.splice should use parentheses ( ) instead of brackets [ ] since it is a function.
The line i++; in the else block is unnecessary.

function combineNumbers()//call to start finding solution by merging numbers
{
    // Save output to local var
    let output = 0;

    //iterates length of equation
    for(let i = 0; i < equation.length;i++)
    {
        //checks if equation[i] is a number
        if(typeof equation[i] === 'number')
        {
            // Adds value to total values var
            ouput += equation[i];
        } else {
            // If equation is not a number do your other stuff here
        }

    }
    // Reset the equation var
    equation = [];
    
    // Log the output
    console.log(ouput);
    return ouput;
}

Answer 8

This seems to be functioning properly, but there are a few issues that need to be addressed.

The check for determining if the equation is a number is incorrect.
The method equation.splice should use parentheses ( ) instead of brackets [ ] since it is a function.
The line i++; in the else block is unnecessary.

function combineNumbers()//call to start finding solution by merging numbers
{
    // Save output to local var
    let output = 0;

    //iterates length of equation
    for(let i = 0; i < equation.length;i++)
    {
        //checks if equation[i] is a number
        if(typeof equation[i] === 'number')
        {
            // Adds value to total values var
            ouput += equation[i];
        } else {
            // If equation is not a number do your other stuff here
        }

    }
    // Reset the equation var
    equation = [];
    
    // Log the output
    console.log(ouput);
    return ouput;
}

Issues arise when the Javascript splice function fails to properly combine array elements

Answer №1

Answer №2

Answer №3

Answer №4

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