CODEWITHSUNDEEP
javascriptreplacefind
Anto
Anto

Reputation: 23

Javascript find and replace text by its position in the text

If I have this string

"Something [10], Something else [10].\nBla bla bla [Not always a number].";

Considering that […] identifies a special element that can be modified,

How would you write a function to have the following result?

var findReplaceElemByPosition = function(delimiters,position,new_value){
    //find all the substrings delimited by the *delimimters*
    //select only the one in a certain *position*
    //replace the old value with the *new_value*
}
var myStrangeString = "Something[10], Something else [10].\nBla bla bla [Not always a number].";
myTransformedString = findReplaceElemByPosition("[]",0,20);
myTransformedString = findReplaceElemByPosition("[]",1,21);
myTransformedString = findReplaceElemByPosition("[]",2,"sometimes just a string");
// expected: myTransformedString = "Something[20], Something else [21].\nBla bla bla [sometimes just a string]."

I found a solution by adding spaces before and after delimiters and splitting the text in an array, but I wonder if there is a more elegant (and professional) solution.

Upvotes: 0

Views: 1073

Answers (1)

Jakub Kotrs
Jakub Kotrs

Reputation: 6211

given an array of inputs like so:

const replacments = [
  20,
  21,
  'some string'
]

you can easily replace all the string occurances by using the callback function of replace method using regexp.

function run(string, replacements) {
  const replaceBy = replacements.slice() // just to be safe
  return string.replace(/\[[^\]]*\]/g, (original) => {
    if (replaceBy.length) {
      return `[${replaceBy.shift()}]`
    }
    return original
  })
}

This function can be run as:

const string = 'Something[10], Something else [10].\nBla bla bla [Not always a number].'
const replacements = [20, 21, 'sometimes just a string']
run(string, replacements)
// returns 'Something[20], Something else [21].\nBla bla bla [sometimes just a string].'

It should now be a matter of juggling with the regex to also make the delimiter a parameter, for which you need to use new RegExp, properly escape every special character and also inside the replacer function re-wrap it with the right delimiter.

Upvotes: 1

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