How to divide strings into equal parts

Question

How to divide a texto with or more than 20,000 characters in equal parts and each part containing 5000 characters? (Nodejs)

I have that function:

textBreak = (data) => {
  const characterCounter = data.text.length;
  const pagesCounter = data.numpages;
  var text = data.text;
  var math = Math.round(characterCounter / pagesCounter) + 3000;
  var index = 0;
  var array = [];
  while (index < characterCounter) {
    array.push(text.substr(math, Math.min(index + math, text.length)));
    index += math;
  }
  console.log('textBreak: sucess');
  return { array, pagesCounter, characterCounter, math }
}
module.exports = textBreak;

Answer 1

What you’re looking for is the function that was declared here:

https://stackoverflow.com/questions/7033639/split-large-string-in-n-size-chunks-in-javascript

function chunkString(str, length) {
    return str.match(new RegExp('.{1,' + length + '}', 'g'));
}

If you prefer to use as a polyfill (as is my case) you can use the code below (it needs to run before initializing anything, after all it is a polyfill):

(window => {
    if (!('chunk' in String)) String.prototype.chunk = function(length) {
        return this.match(new RegExp(`.{1,${length}}`, 'g'))
    }
})(window)

When adding polyfill, now simply call the function in any string field, like this:

console.log('12345678'.chunk(2))
// result: (4) ["12", "34", "56", "78"]

Answer 2

A possible solution would be to make a while in the string according to its size (length) and within the while, you go break the string with substring, taking a chunk of it and adding it to an array, so the string decreases as the array takes new positions.

function breakString(string, size) {
  //Valor default de 5000
  size = size || 5000;

  let breakStr = [];

  while (string.length > 0) {
    breakStr.push(string.substring(0,size));
    string = string.substring(size,string.length);
  }

  return breakStr;
}

let bigString = "abcdefghij".repeat(2000);

//Quebrar com o tamanho padrão de  5000
console.log(breakString(bigString));

//Quebrar de 130 em 130...
console.log(breakString(bigString, 130));

//Exemplo para verificar se a string de entrada é a mesma de saída
console.log( bigString == breakString(bigString, 147).reduce( (acc, value) => acc += value , "") );