How to use str.replace with many find/replace pairs in JavaScript

Question

I need a function in JavaScript that takes one string as input, replaces many substrings with their corresponding values, then returns the result. For example:

function findreplace(inputStr) {
    const values = {"a": "A",
              "B": "x",
              "c": "C"};

    // In this example, if inputStr is "abc", then outputStr should be "AbC".

    return outputStr
}

I know how to individually find and replace, but I was wondering if there was an easy way to do this with many pairs of (case-sensitive) values at once.

Thank you!

For now, they will always be single characters, though that may change in the future. It is preferable that the solution works with any substrings, but it isn't necessary. — Ben Soyka
– Ben Soyka, Commented Oct 13, 2019 at 18:29

connexo · Accepted Answer · 2019-10-13 18:26:08Z

1

Just iterate over values with the help of Object.entries(values):

function findreplace(inputStr) {
  const values = {
    "a": "A",
    "B": "x",
    "c": "C"
  };
  for (const [search, replace] of Object.entries(values)) {
    inputStr = inputStr.replace(search, replace);    
  }
  return inputStr;
}

console.log(findreplace("abc"));

answered Oct 13, 2019 at 18:26

connexo

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Code Maniac · Accepted Answer · 2019-10-13 18:31:27Z

1

You can join keys to build a regex and then replace accordingly

function findreplace(inputStr) {
  let values = { "a": "A", "B": "x", "c": "C" };
  let regex = new RegExp("\\b" + Object.keys(values).join('|') + "\\b", 'g')
  return inputStr.replace(regex, (m) => values[m] )
}

console.log(findreplace('aBc'))
console.log(findreplace('AbC'))
console.log(findreplace('ABC'))

edited Oct 13, 2019 at 18:31

answered Oct 13, 2019 at 18:24

Code Maniac

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