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JS References

JavaScript Objects HTML DOM Objects


JavaScript String Search

JavaScript Search Methods

  • String indexOf()
  • String lastIndexOf()
  • String search()
  • String match()
  • String matchAll()
  • String includes()
  • String startsWith()
  • String endsWith()

JavaScript String indexOf()

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

Example

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

Note

JavaScript counts positions from zero.

0 is the first position in a string, 1 is the second, 2 is the third, ...


JavaScript String lastIndexOf()

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

Example

let text = "Please locate where 'locate' occurs!";
text.lastIndexOf("locate");
Try it Yourself »

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

Example

let text = "Please locate where 'locate' occurs!";
text.lastIndexOf("John");
Try it Yourself »

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

Example

let text = "Please locate where 'locate' occurs!";
text.indexOf("locate", 15);
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 text = "Please locate where 'locate' occurs!";
text.lastIndexOf("locate", 15);
Try it Yourself »

JavaScript String search()

The search() method searches a string for a string (or a regular expression) and returns the position of the match:

Examples

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



JavaScript String match()

The match() method returns an array containing the results of matching a string against a string (or a regular expression).

Examples

Perform a search for "ain":

let text = "The rain in SPAIN stays mainly in the plain";
text.match("ain");
Try it Yourself »

Perform a search for "ain":

let text = "The rain in SPAIN stays mainly in the plain";
text.match(/ain/);
Try it Yourself »

Perform a global search for "ain":

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

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

let text = "The rain in SPAIN stays mainly in the plain";
text.match(/ain/gi);
Try it Yourself »

Note

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

Read more about regular expressions in the chapter JS RegExp.


JavaScript String matchAll()

The matchAll() method returns an iterator containing the results of matching a string against a string (or a regular expression).

Example

const iterator = text.matchAll("Cats");
Try it Yourself »

If the parameter is a regular expression, the global flag (g) must be set, otherwise a TypeError is thrown.

Example

const iterator = text.matchAll(/Cats/g);
Try it Yourself »

If you want to search case insensitive, the insensitive flag (i) must be set:

Example

const iterator = text.matchAll(/Cats/gi);
Try it Yourself »

Notes

matchAll() is an ES2020 feature.

matchAll() does not work in Internet Explorer.


JavaScript String includes()

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

Otherwise it returns false.

Examples

Check if a string includes "world":

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

Check if a string includes "world". Start at position 12:

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

Notes

includes() is case sensitive.

includes() is an ES6 feature.

includes() is not supported in Internet Explorer.


JavaScript String startsWith()

The startsWith() method returns true if a string begins with a specified value.

Otherwise it returns false:

Examples

Returns true:

let text = "Hello world, welcome to the universe.";
text.startsWith("Hello");
Try it Yourself »

Returns false:

let text = "Hello world, welcome to the universe.";
text.startsWith("world")
Try it Yourself »

A start position for the search can be specified:

Returns false:

let text = "Hello world, welcome to the universe.";
text.startsWith("world", 5)
Try it Yourself »

Returns true:

let text = "Hello world, welcome to the universe.";
text.startsWith("world", 6)
Try it Yourself »

Notes

startsWith() is case sensitive.

startsWith() is an ES6 feature.

startsWith() is not supported in Internet Explorer.


JavaScript String endsWith()

The endsWith() method returns true if a string ends with a specified value.

Otherwise it returns false:

Examples

Check if a string ends with "Doe":

let text = "John Doe";
text.endsWith("Doe");
Try it Yourself »

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

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

Try it Yourself »

Notes

endsWith() is case sensitive.

endsWith() is an ES6 feature.

endsWith() is not supported in Internet Explorer.


Complete String Reference

For a complete String reference, go to our:

Complete JavaScript String Reference.

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