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

Question

Being fairly new to JavaScript, I'm unable to discern when to use each of these.

Can anyone help clarify this for me?

Penetrant

Answer 1

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

Jobye

any reference to support this claim? – Proudfoot

Also, search will evaluate a string into a regex even if you don't want to. – Advertisement

@cregox's comment is important - try "hello.".search(".") - it returns 0, not 5 because . is the regex token for "any character" – Brigid

'hello'.indexOf(undefined) returns -1, 'hello'.search(undefined) returns 0 – Underclay

Answer 2

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

Ability

Answer 3

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

Amorita

Answer 4

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.

Metametabel

Answer 5

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

Check this reference:

• search
• indexOf

Allison

Answer 6

IndexOf() - it accepts string literals or string objects but not regular expressions. It also accepts a zero-based integer value to start its search from, e.g.:

1. "babyelephant".indexOf("e"); // gives you 4
2. "babyelephant".indexOf("e",5); // gives you 6 as the search starts from 6th position or 5th index.
3. var m= /e/; "babyelephant".indexOf(m); //gives -1 as it doesnt accepts regular expressions.

Search() - accepts both string literals or string objects and regular expressions. But it doesn't accepts a index to start the search from.

Mohican

What does it return for "baby/e/lephant".indexOf(m);? – Hygro

good one.. it will return 4..because /e/ string is present..but if you want to find a regex "e" you aren't going to get the desired result. UMM maybe i should modify my answer to indexOf() tries to find the regex as a string literal and not as a regex. – Mohican

Answer 7

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

IndexOf

Search

Ortensia

Search does return an offset. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Towering

Answer 8

Besides all the other considerations already mentioned indexOf is faster by a very large margin, if you don't need to do funky regex and are just doing a simple find then do not use search. robisrob asked for some evidence so I whipped up a quick test.

Starting...
  IndexOf test - loop count 10000000
  IndexOf test end - duration: 4.600000023841858ms
  Search test - loop count 10000000
  Search test end - duration: 1221.6999999284744ms
All Done

That is a significant difference, only use search if you are going to be using regular expressions.

I can post the test code if anyone is interested.

Acrolein

Answer 9

Without a regex, there is no practical difference between indexOf and search.

The below example gives a live demo:

function FromSearch() {

  var str = document.getElementById("demo").innerText;
  var n = str.search("difference");
  document.getElementById("Location").innerHTML = n;
}

function FromindexOf() {
  var str = document.getElementById("demo").innerText;
  var n = str.indexOf("difference");
  document.getElementById("Location").innerHTML = n;
}

<p id="demo">Without a <a href='http://www.w3schools.com/js/js_regexp.asp'>regex</a>, there is no practical difference between <a href='http://www.w3schools.com/jsref/jsref_indexof.asp'>indexOf</a> and <a href='http://www.w3schools.com/jsref/jsref_search.asp'>search</a>
</p>

<button onclick="FromSearch()">From search</button>

<button onclick="FromindexOf()">From indexOf</button>

<p>Location of difference in the above sentence is:</p>

<mark id="Location"></mark>

Sunglass

There is a significant difference: search converts a string into a RegExp, so for instance, str.search("d........e"); will also match at character 39. – Snatch