What is the difference between indexOf() and search()?

If your situation requires the use of a regular expression, use the search() method, otherwise; the indexOf() method is more performant.

indexOf is for plain substrings, search is for regular expressions.

indexOf() and search()

• common in both

  i) return the first occurrence of searched value

  ii) return -1 if no match found

  let str='Book is booked for delivery'
  str.indexOf('b')   // returns position 8
  str.search('b')    // returns position 8 
  

• special in indexOf()

  i) you can give starting search position as a second argument

  str.indexOf('k')   // 3
  str.indexOf('k',4) // 11 (it start search from 4th position) 
  

• special in search()

search value can be regular expression

str.search('book') // 8
str.search(/book/i)  // 0   ( /i =case-insensitive   (Book == book)

reference

The search function (one description here) takes a regular expression, which allows you to match against more sophisticated patters, case-insensitive strings, etc., while indexOf (one description here) simply matches a literal string. However, indexOf also allows you to specify a beginning index.

I think the main difference is that search accept regular expressions.

Check this reference:

• search
• indexOf

Search finds it's matches with a regular expression, but has no offsets. IndexOf uses literals to match, but has an offset.

IndexOf

Search