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JavaScript String Search

JavaScript methods for searching strings:

  • String.indexOf()
  • String.lastindexOf()
  • String.startsWith()
  • String.endsWith()

String.indexOf()

The indexOf() method returns the index of (the position of) the first occurrence of a specified text in a string:

Example

let str = "Please locate where 'locate' occurs!";
str.indexOf("locate")    // Returns 7
Try it Yourself »

JavaScript counts positions from zero.
0 is the first position in a string, 1 is the second, 2 is the third ...


String.lastIndexOf()

The lastIndexOf() method returns the index of the last occurrence of a specified text in a string:

Example

let str = "Please locate where 'locate' occurs!";
str.lastIndexOf("locate")    // Returns 21
Try it Yourself »

Both indexOf(), and lastIndexOf() return -1 if the text is not found:

Example

let str = "Please locate where 'locate' occurs!";
str.lastIndexOf("John")    // Returns -1
Try it Yourself »

Both methods accept a second parameter as the starting position for the search:

Example

let str = "Please locate where 'locate' occurs!";
str.indexOf("locate", 15)    // Returns 21
Try it Yourself »

The lastIndexOf() methods searches backwards (from the end to the beginning), meaning: if the second parameter is 15, the search starts at position 15, and searches to the beginning of the string.

Example

let str = "Please locate where 'locate' occurs!";
str.lastIndexOf("locate", 15)    // Returns 7
Try it Yourself »

String.search()

The search() method searches a string for a specified value and returns the position of the match:

Example

let str = "Please locate where 'locate' occurs!";
str.search("locate")     // Returns 7
Try it Yourself »

Did You Notice?

The two methods, indexOf() and search(), are equal?

They accept the same arguments (parameters), and return the same value?

The two methods are NOT equal. These are the differences:

  • The search() method cannot take a second start position argument.
  • The indexOf() method cannot take powerful search values (regular expressions).

You will learn more about regular expressions in a later chapter.



String.match()

The match() method searches a string for a match against a regular expression, and returns the matches, as an Array object.

Example 1

Search a string for "ain":

let text = "The rain in SPAIN stays mainly in the plain";
text.match(/ain/g)    // Returns an array [ain,ain,ain]
Try it Yourself »

Read more about regular expressions in the chapter JS RegExp.

If the regular expression does not include the g modifier (to perform a global search), the match() method will return only the first match in the string.

Syntax

string.match(regexp)
regexp Required. The value to search for, as a regular expression.
Returns: An Array, containing the matches, one item for each match, or null if no match is found

Example 2

Perform a global, case-insensitive search for "ain":

let text = "The rain in SPAIN stays mainly in the plain";
text.match(/ain/gi)   // Returns an array [ain,AIN,ain,ain]
Try it Yourself »

String.includes()

The includes() method returns true if a string contains a specified value.

Example

let text = "Hello world, welcome to the universe.";
text.includes("world")    // Returns true
Try it Yourself »

Browser Support

String.includes() is not supported in Internet Explorer.

Chrome 41 Edge 12 Firefox 40 Safari 9 Opera 28
Mar 2015 Jul 2015 Aug 2015 Oct 2015 Mar 2015

Syntax

string.includes(searchvalue, start)
searchvalue Required. The string to search for
start Optional. Default 0. Position to start the search
Returns: Returns true if the string contains the value, otherwise false
JS Version: ES6 (2015)

Check if a string includes "world", starting the search at position 12:

let text = "Hello world, welcome to the universe.";
text.includes("world", 12)    // Returns false
Try it Yourself »

String.startsWith()

The startsWith() method returns true if a string begins with a specified value, otherwise false:

Example

let text = "Hello world, welcome to the universe.";

text.startsWith("Hello")   // Returns true
Try it Yourself »

Syntax

string.startsWith(searchvalue, start)

Parameter Values

Parameter Description
searchvalue Required. The value to search for.
start Optional. Default 0. The position to start the search.

Examples

let text = "Hello world, welcome to the universe.";

text.startsWith("world")    // Returns false
let text = "Hello world, welcome to the universe.";

text.startsWith("world", 5)    // Returns false
let text = "Hello world, welcome to the universe.";

text.startsWith("world", 6)    // Returns true
Try it Yourself »

Note: The startsWith() method is case sensitive.

The startsWith() method is not supported in Internet Explorer.

The first browser versions with full support was:

Chrome 41 Edge 12 Firefox 17 Safari 9 Opera 28
Mar 2015 Jul 2015 Aug 2015 Oct 2015 Mar 2015

String.endsWith()

The endsWith() method returns true if a string ends with a specified value, otherwise false:

Example

Check if a string ends with "Doe":

var text = "John Doe";
text.endsWith("Doe")    // Returns true
Try it Yourself »

Syntax

string.endswith(searchvalue, length)

Parameter Values

Parameter Description
searchvalue Required. The value to search for.
length Optional. The length to search.

Check in the 11 first characters of a string ends with "world":

let text = "Hello world, welcome to the universe.";
text.endsWith("world", 11)    // Returns true

Try it Yourself »

Note: The endsWith() method is case sensitive.

The endsWith() method is not supported in Internet Explorer.

The first browser versions with full support was:

Chrome 51 Edge 15 Firefox 54 Safari 10 Opera 38
May 2016 Apr 2017 Jun 2017 Sep 2016 Jun 2016


Complete String Reference

For a complete reference, go to our Complete JavaScript String Reference.

The reference contains descriptions and examples of all string properties and methods.