How to insert new line characters at correct intervals in a string?

Question

I'm working on a challenge that asks to insert new line characters at specific intervals in a string. Examples of expected returns:

insertNewLine('Happiness takes wisdom and courage', 20) => 'Happiness takes\nwisdom and courage'

insertNewLine('Happiness takes wisdom and courage', 30) => 'Happiness takes wisdom and\ncourage'

So far I've been thinking that an easy algorithm to implement would be this:

split the string into equal chunks, passed on the desired width
find the last index of space in each chunk and replace it with \n

Clearly the algorithm is flawed because this is the return I'm getting, mainly because I'm looping over the array of string chunks and always adding a newline char in each chunk. This is the correct output:

insertNewLine('Happiness takes wisdom and courage', 20) => 'Happiness takes\nwisdom and\ncourage'

What would be a better algorithm to achieve the expected results?

Here's the code too:

const _ = require('underscore')
const insertNewLine = (text, width) => {
  if (width < 15) return 'INVALID INPUT';
  if (text.length <= width) return text;
  else {
    const arrayOfText = text.split('');
    const temparray = [];
    for (let i = 0; i < arrayOfText.length; i += width) {
      temparray.push(arrayOfText.slice(i, i + width));
    }
    return temparray.map((elem, i, arr) => {
      elem[_.lastIndexOf(elem, ' ')] = '\n';
      return elem.join('');
    }).join('');
  }
};

Possible duplicate of [JavaScript: How can I insert a string at a specific index](https://stackoverflow.com/questions/4313841/javascript-how-can-i-insert-a-string-at-a-specific-index) — anteAdamovic, Sep 18 '17 at 11:47

score 1 · Accepted Answer · edited Sep 18 '17 at 14:12

1

function replaceSpace(tx,n) { //tx is the text and n is the number
    var br=0;
    while(n-->0) {
        if(tx[n]==" ") {
            br = n;
            break;
        }
    }
    return tx.substring(0,br)+"\n"+tx.substring(br,tx.length);
}

edited Sep 18 '17 at 14:12

MD. Khairul Basar

4,976
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41
59

answered Sep 18 '17 at 11:50

Vinod kumar G

639
6
17

Line breaks should not be inserted in the middle of a word. – Klas Lindbäck Sep 18 '17 at 12:04
What is the meaning of the 20 -- is it the 20th place ? need little clarification in it..insertNewLine('Happiness takes wisdom and courage', 20) – Vinod kumar G Sep 18 '17 at 12:05
It means lines must be no longer than 20 chars (excluding the newline), but may be shorter since the line break must be at a (white)space. – Klas Lindbäck Sep 18 '17 at 12:08
20 would be the desired max width of each line. – alanionita Sep 18 '17 at 12:09
please check now – Vinod kumar G Sep 18 '17 at 14:06
Worked perfectly, just added a br + 1 at the end substring - I wanted to fully replace the space and avoid having spaces at the beginning of new lines "return text.substring(0, br) + '\n' + text.substring(br + 1, text.length);" – alanionita Sep 18 '17 at 19:36

krishnar · Answer 2 · 2017-09-18T12:08:15.640

0

Try this

function insertNewLine(str, pos){
    var str = str.split("")
    for (var i = pos-1; i < str.length-1; i+=pos) { 
        str[i] = "\n"
     }
      return str.join("")
 }

edited Sep 18 '17 at 12:08

answered Sep 18 '17 at 11:47

krishnar

2,537
9
23

How to insert new line characters at correct intervals in a string?

2 Answers2