JavaScript: Regex to replace this "2018Jun12-2018Jul11" date string with this "Jun 12, 2018 - Jul 11, 2018" date string

Question

If I have the following string:

var str = "2018Jun12-2018Jul11";

Is there a regular expression that I could use to convert it to: "Jun 12, 2018 - Jul 11, 2018" with str.replace()?

Answer 1

Though this involves a bit of string formatting logic via a "replacer" callback, one solution that is based on String#replace() would be:

const input = `2018Jun12-2018Jul11`;
const output = input.replace(
  /* Search for matches of this pattern, and extract groups */
  /(\d+)([a-z]+)(\d+)/gi, 
  /* Replacer function formats the extracted values as required */
  (_,year,month,date) => `${month} ${date}, ${year}`
)
/* If you need white space around the hyphen */
.split('-').join(' - ')

console.log(input, ' -> ', output)

The idea here is to match any occurance of pattern "year number (\d+),month string [a-z]+, date number (\d+)" in your input string. The use of ( ) in the pattern causes corresponding values to be extracted from the pattern match. The replacer callback returns a string that rearranges those extracted values to the desired format. This string becomes the replacement value for the match in the output.

Hope that helps