Replace all variables in string using RegEx

Question

Using a combination of a couple of previous answers I've tried to put together a RegEx that'll allow me to replace all occurrences of anything within curly braces

I got this far, but it doesn't seem to work

var str = "The {type} went to the {place}";


var mapObj = {
   type: 'Man',
   place: "Shop"

};
var re = new RegExp(/(?<=\{)Object.keys(mapObj).join("|")(?=\})/, "gim");
str = str.replace(re, function(matched){
  return mapObj[matched.toLowerCase()];
});

console.log(str);

I added (?<={) and (?=}) to the previous answer to have it only match occurrences where the key was within curly braces

Previous Answer - Replace multiple strings with multiple other strings

I would try simply /\{([^}]+)\}/ to match on any string surrounded by curly braces. — Taplar
– Taplar, Commented Jan 3, 2020 at 18:01

Ori Drori · Accepted Answer · 2020-01-03 18:12:51Z

3

Use a capture group, and you'll get the value as the 2nd param of the replace callback:

var str = "The {type} went to the {place}";

var mapObj = {
  type: 'Man',
  place: "Shop"

};

str = str.replace(/\{([^{}]+)\}/gim, function(_, c) {
  return mapObj[c.toLowerCase()] || `{${c}}`;
});

console.log(str);

edited Jan 3, 2020 at 18:12

answered Jan 3, 2020 at 18:01

Ori Drori

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4 Comments

MonkeyZeus Over a year ago

Given the nature of OP's question I would imagine there will be instances where a variable in the string does not have a match in the mapObj.

MonkeyZeus Over a year ago

Something like return mapObj[c.toLowerCase()] !== undefined ? mapObj[c.toLowerCase()] : '{'+c+'}'; would fix it.

Tam2 Over a year ago

That works perfectly, added the suggestion from @MonkeyZeus as there could be instances where a variable doesn't match a key within mapObj so better to return it as it was

MonkeyZeus Over a year ago

@TamoorMalik I would suggest using the return statement from my comment because it would properly handle mismatched data types so that you could do something like type: 0 reliably.

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