替换javascript中的正则表达式子字符串

Question

I have two strings which could be the value of the variable 'url'

s1 = "example.com/s/ref=f1_a2?k=awesome";    //ref tag is at the middle

s2 = "example.com/s?k=underground&ref=b3_a6"; //ref tag is at the end

I need to replace the values of ref with a string 'answer'

Expected output:

s1 = "example.com/s/ref=answer?k=awesome"

s2 = "example.com/s?k=underground&ref=answer"

I tried using the following regex:

const regex = /ref=(\S)\\?/;
url = url.replace(regex, 'answer')

This just replaces the 'ref=' substring. But I would like to replace it's value. And it has to perform the same if the 'ref' is in the middle of the string or at the end.

Answer 1

 const regex = /(&?)ref=(\\w+)(\\?|&)?/gm; const str = "example.com/s/ref=f1_a2?k=awesome" const str2= "example.com/s?k=underground&ref=b3_a6"; const subst = `$1ref=answer$3`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); const result2 = str2.replace(regex, subst); console.log('result for s1 ', result); console.log('result for s2 ', result2);