Pause and Persist

Question

Pause and Persist

Can someone help me clarify a code issue I'm facing? I have a piece of code that checks an array for overlapping values based on different criteria. This code specifically deals with rows and columns in a Google Sheet using GAS. Here's what I currently have:

  var e = [[2,4,3,4,2],[1,5,3,6,2],[2,4,3,4,1],[1,4,3,6,1],[2,4,3,6,5]];
  var i; //id of entry to check
  var j; //id of element to check
  var k; //id of entry to compare

  for (i in e){ //2D ARRAY ARRAY
      for (k in e){ //ELEMENT TO COMPARE
           if (e[i][2] === e[k][2] && e[i][3] === e[k][3] && e[i][0] && e[i][0] >= e[k][0] && e[i][1] <= e[k][1] && e[i][4] <= e[k][4] &&  i !=k){
             e.splice(i,1);
             continue;
           }
      }
  }
  return e;

I had to include the continue; statement because without it, the code failed when the last array was also marked for removal using `splice`. I initially thought using break instead of continue would solve the issue, but it didn't work as expected. Does break permanently stop that specific section of code?

Thanks in advance

EDIT: Scratch that, the code still doesn't work even with `continue`. Still trying to figure this out!

javascript

Answer 1

Answer №1

continue instantly goes to the next iteration, for example:

  while(true) {
    console.log("a");
    continue;
    console.log("b");
 }

only "a" will be logged because it would jump back to the beginning of the loop whenever it encounters continue. Placing continue at the end of the loop (similar to your code) results in no action, just skipping an empty line.

I assumed break would exit to the outer loop

Indeed, that's what happens, and it is beneficial as there's no need to check for duplicates if the element has already been removed; removing it twice wouldn't make sense.

The issue arises when splice alters the indexes. If you remove the fourth element, the fifth one becomes the fourth one, but the loop continues to the fifth element without revisiting the fourth (which is now different). Thus, you should backtrack by one element before breaking out of the loop:

 for(let i = 0; i < e.length; i++) {
   for(let k = 0; k < e.length; k++) {
      if(i === k) continue; // < appropriate scenario
      if(/* condition checks */) {
        e.splice(i, 1); // remove the element
        i--; // go back one position due to reordering
        break; // exit inner loop
     }
   }
 }

In my opinion:

1) I prefer using

for(const [i, value] of arr.entries()

over for..in

2) Naming indexes properly makes code more readable than having to remember what arr[i][2] represents:

  const [idA, someValueA] = e[i];
  const [idB, someValueB] = e[k];
  if(idA === idB && someValueA <= someValueB // ...

3) Using a better variable name than e is advisable.

Answer 2

continue instantly goes to the next iteration, for example:

  while(true) {
    console.log("a");
    continue;
    console.log("b");
 }

only "a" will be logged because it would jump back to the beginning of the loop whenever it encounters continue. Placing continue at the end of the loop (similar to your code) results in no action, just skipping an empty line.

I assumed break would exit to the outer loop

Indeed, that's what happens, and it is beneficial as there's no need to check for duplicates if the element has already been removed; removing it twice wouldn't make sense.

The issue arises when splice alters the indexes. If you remove the fourth element, the fifth one becomes the fourth one, but the loop continues to the fifth element without revisiting the fourth (which is now different). Thus, you should backtrack by one element before breaking out of the loop:

 for(let i = 0; i < e.length; i++) {
   for(let k = 0; k < e.length; k++) {
      if(i === k) continue; // < appropriate scenario
      if(/* condition checks */) {
        e.splice(i, 1); // remove the element
        i--; // go back one position due to reordering
        break; // exit inner loop
     }
   }
 }

In my opinion:

1) I prefer using

for(const [i, value] of arr.entries()

over for..in

2) Naming indexes properly makes code more readable than having to remember what arr[i][2] represents:

  const [idA, someValueA] = e[i];
  const [idB, someValueB] = e[k];
  if(idA === idB && someValueA <= someValueB // ...

3) Using a better variable name than e is advisable.

Answer 3

Answer №2

To escape from nested loops, you can utilize a labeled break statement. For example:

var count = 0;
mainLoop:
for(var x = 0; x < 10; x++){
  for(var y = 0; y < 10 ; y++){
    if(x == 5 && y == 5){
      break mainLoop;
    }
    count++;
  }
}

Answer 4

To escape from nested loops, you can utilize a labeled break statement. For example:

var count = 0;
mainLoop:
for(var x = 0; x < 10; x++){
  for(var y = 0; y < 10 ; y++){
    if(x == 5 && y == 5){
      break mainLoop;
    }
    count++;
  }
}

Pause and Persist

Answer №1

Answer №2

Similar questions

Extracting data with Jquery Repeater in jQuery

Ways to verify the existence of a particular word within a nested array of objects

What is the best way to retrieve data from PHP and format it into JSON for use in my jQuery script?

Obtaining a cookie from a browser that has been dropped by a different application

if a user does not click on an element in jQuery

Storing a table structure in a variable using JavaScript

Tips for arranging years in descending order in the material-ui Date Picker's calendar interface

Unable to generate a fresh directory with mongoose and express

The challenges encountered with JSONP/Ajax Script - displaying 'Undefined'

Tips for transforming a hover menu into a clickable menu

Get the value of the button that has been clicked

The error message keeps appearing consistently. What is the best way to manage this error?

What is the best method for sending a JavaScript variable to the server and back again?

I'm experiencing issues with my AJAX as it fails to post or respond after the user clicks on the submit

Transferring map functionality to a separate file

Monitor changes in the select tag to display the updated value and output

Is there a way to properly dissect or iterate through this?

Using javascript to eliminate a block of HTML code

Invoke the method in customButton component of fullcalendar

Redirect based on the geographical location of IP addresses (Geo-IP)