How to format text into multiple lines in JavaScript

Question

what I am trying to do is have a text "box" that has a certain line length in width without cutting any words in half. what I am trying to do at the moment is cut the text into lines of n length, and then I am trying to repair words by knowing when the next space is. this is what I have at the moment but it does not fully work and only repairs some of the words

function TextBox(length,text){
  array = [];
  test = /[A-Za-z]+/g;
  //cutting the text up
  for (i= 0;i < Math.ceil(text.length / length); i ++){
    array.push(text.slice(i * length,Math.min((i + 1) * length,text.length)));
  }
  //in case it ruins the lines the first time round
  for (z = 0; z < 3; z++){
    //reformatting the code
    for (i = 0; i < array.length - 1; i ++){
      if (test.test(array[i][array[i].length - 1])){
        array[i] += array[i+1].substr(0,array[i+1].indexOf(' ') + 1);
        array[i + 1] = array[i + 1].substr(array[i + 1].indexOf(' ') + 1);
      }
    }
  }
  //for debugging
  console.log(array);
}
TextBox(5,"i like to eat cheese when I am hungry");

EDIT an example of an input is: "i like to eat cheese when I am hungry" and I want something like: [ "i like", "to eat", "cheese", "when I", "am hungry" ] what I am getting out right now is this: [ 'i like ', 'to ', 'eat c', notice the "c" from cheese 'heese', ' when ', 'I am ', 'hung', 'ry' ] and the "ry" from hungry

with the line length around n (5 in this example) characters long.

I have tried adding and removing the extra for loop but from what I can tell it helps to format it.

if you know what I am doing wrong, or an easier way to do this that would be great.

Can you post a couple inputs and the expected output from each? — CertainPerformance
– CertainPerformance, Commented Dec 7, 2018 at 4:02
did you mean is wrapping the text? As @CertainPerformance said, please add input and expected output. — Fadhly Permata
– Fadhly Permata, Commented Dec 7, 2018 at 4:04

CertainPerformance · Accepted Answer · 2018-12-07 04:45:53Z

One option would be to construct a regular expression that alternates between 5 characters, or 4 characters, or 7 characters, etc:

.....   // 5 characters
....    // 4 characters
......  // 6 characters
...     // 3 characters
....... // 7 characters

And precede those alternations with

(?! )

to ensure that the matched line doesn't start with a space, and end the alternations with

(?= |$)

to ensure that the match ends right before a space (or the end of the string).

Then, all you have to do is execute the pattern .match on the input:

function TextBox(length,text){
   const alternations = Array.from(
     { length: length * 2 - 1 },
     (_, i) => {
       const charCount = i % 2 === 0
       ? length - i / 2
       : length + (i - 1) / 2 + 1;
       return '.'.repeat(charCount);
     }
   );
   // in case none of the above alternations matched, lazy-match characters
   // until coming to a character followed by a space or the end of the string:
   alternations.push('.+?');

   const pattern = new RegExp('(?! )(?:' + alternations.join('|') + ')(?= |$)', 'g');
   console.log(pattern);
   return text.match(pattern);
}
console.log(TextBox(5,"i like to eat cheese when I am hungry"));
console.log(TextBox(8,"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum"));

this method seems to skip the last word/segment of the string, sorry jumped on the code too fast, it works now

IronGeek · Accepted Answer · 2018-12-07 04:53:59Z

Here is another take using only Array split() and .reduce()

function TextBox(length,text){
  var array = [];  
  
  text.split(' ').reduce(function(prev, cur) {
    var next = [prev, cur].join(' ').trim();
    
    if (next.length <= length) {
    	return next;
    } else {
    	array.push(next);
    	return '';
    }
  });   
  
  console.log(array);
}

TextBox(5, 'i like to eat cheese when I am hungry');

TextBox(8, 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum')

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How to format text into multiple lines in JavaScript

with the line length around n (5 in this example) characters long.

I have tried adding and removing the extra for loop but from what I can tell it helps to format it.

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Collectives™ on Stack Overflow

with the line length around n (5 in this example) characters long.

I have tried adding and removing the extra for loop but from what I can tell it helps to format it.

2 Answers 2

1 Comment

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