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I have a string 3-5,10-15,20 and I want to insert p before every number. I wanted to just find each '-' and ',' and insert a 'p' after each one, and then one at the beginning. Looping over it requires manipulating the string you're looping over, which wasn't working quite well for me. I feel like this is such a simple task, but I'm getting stuck. Any help would be appreciated.

The final result should look like p3-p5,p10-p15,p20. This is what I tried:

input = `p${input}`;
for (let i = 0; i < input.length; i++) {
   if (input[i] === '-' || input[i] === ',') {
    input = `${input.slice(0, i + 1)}p${input.slice(i + 1)}`;
   }
}
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3
  • ok , so where exactly are you implementing this? Commented Sep 6, 2020 at 16:59
  • 2
    please add the wanted result and your try. Commented Sep 6, 2020 at 17:00
  • Edited answer for clarity. Commented Sep 6, 2020 at 17:12

2 Answers 2

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5

You could search for digits and replace the digits with added value.

var string = '3-5,10-15,20',
    result = string.replace(/\d+/g, 'p$&');

console.log(result);

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2 Comments

Can you explain the second argument in replace?
it takes the string for each replacement and $& is the matched value, all connected digits in this case.
2

You could use a regex to match the - and the , character and replace them using a group.

const input = '3-5,10-15,20';

console.log(input.replace(/([-,])/g, "$1p"));

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5 Comments

Can you explain a little more? Esp. the $1?
the first digits have no 'p'.
@pianoman102 The regex [-,] matches a - or , this character is placed in group 1 by surrounding it with parentheses. $1 will replace the match with the contents of group 1 the p behind $1 adds a p behind the match.
$1 is a special replacement pattern in javascript String.replace() that inserts the first parenthesized submatch string in this case [,-]
See: developer.mozilla.org/nl/docs/Web/JavaScript/Reference/…

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