Need to replace a character in a string with two new values

Question

var Str = "_Hello_";
var newStr = Str.replaceAll("_", "<em>");
console.log(newStr);

it out puts <em>Hello<em> I would like it to output <em>Hello</em> but I have no idea how to get the </em> on the outer "_", if anyone could help I would really appreciate it. New to coding and finding this particularly difficult.

Answer 1

Replace two underscores in one go, using a regular expression for the first argument passed to replaceAll:

var Str = "_Hello_";
var newStr = Str.replaceAll(/_([^_]+)_/g, "<em>1ドル</em>");
console.log(newStr);

NB: it is more common practice to reserve PascalCase for class/constructor names, and use camelCase for other variables. So better str =, ...etc.

• Heretic Monkey: Certainly this is a dupe...
• cmgchess: now OP has a new question: what is a regular expression :D
• trincot: Just in case: what is a regular expression

Answer 2

I would phrase this as a regex replacement using a capture group:

var str = "_Hello_ World!";
var newStr = str.replace(/_(.*?)_/g, "<em>1ドル</em>");
console.log(newStr);

• Veer Thakrar: Thank you very much that code works, just to better my understanding, would you be able to explain the (.*?) and 1,ドル as I have not seen this before
• Tim Biegeleisen: The 1ドル in the replacement is called a capture group, and it refers to the (.*?) term in the regex pattern, which is whatever sits in between the underscores.
• Veer Thakrar: Thank you, so if I wanted to apply it to a larger string, with words that both have and don’t have underscores, what would I have to change?
• Tim Biegeleisen: This answer should work just the same already.