Get the text at the specified row and column

Question

If I have a string like so:

const string = [
  'some text here',
  'some more text here',
  'more more more text here',
  'just for some variety here'
].join('\n')

And if I have a start line number and column number, and an end row number and column number, how can I get the text at those points?

For example, if the line number data was:

const lineData = {
  start: {row: 2, column: 5},
  end: {row: 3, column: 4}
}

I should get 'more text here\nmore'

Answer 1

Here I've written a solution. I've converted your string array into a 2D array and concatenated the characters from start to end. Follow this-

const string = [
  'some text here',
  'some more text here',
  'more more more text here',
  'just for some variety here'
];

const string2d = string.map(line => line.split(''));

const lineData = {
  start: {row: 2, column: 5},
  end: {row: 3, column: 4}
}

const {start: {row: startRow, column: startColumn}, end: {row: endRow, column: endColumn}} = lineData;
let ans = '';

// Run from start row to the end row
for (let i = startRow - 1; i <= endRow - 1; i++) {
  let j = 0;
  
  // For the first row the column starts from the start column
  // And the other cases it starts from 0
  if (i === startRow - 1) {
    j = startColumn - 1;
  }
  
  // Concat the characters from j to length of the line.
  // But for the endRow line concat to the end column
  while (j < string2d[i].length) {
    ans += string2d[i][j];
    j++;
    if (i === endRow - 1 && j > endColumn) break;
  }
  
  // Append a newline after every line
  ans += "\n";
}

console.log(ans);