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JavaScript String Search

JavaScript String indexOf()

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

<p>The indexOf() method returns the position of the first occurrence of a specified text:</p>

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.indexOf(“locate”);

</script>

</body>

</html>

Output

JavaScript String Methods

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

7

JavaScript String lastIndexOf()

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

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

<p>The lastIndexOf() method returns the position of the last occurrence of a specified text:</p>

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.lastIndexOf(“locate”);

</script>

</body>

</html>

Output

JavaScript String Methods

The lastIndexOf() method returns the position of the last occurrence of a specified text:

21

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

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

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.indexOf(“John”);

</script>

</body>

</html>

Output

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

-1

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

<p>The indexOf() method accepts a second parameter as the starting position for the search:</p>

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.indexOf(“locate”,15);

</script>

</body>

</html>

Output

JavaScript String Methods

The indexOf() method accepts a second parameter as the starting position for the search:

21

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

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

<p>The lastIndexOf() method accepts a second parameter as the starting position for the search.</p>

<p>Remember that the lastIndexOf() method searches backwards, so position 15 means start the search at position 15, and search to the beginning.</p>

<p>Position 15 is position 15 from the beginning.</p>

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.lastIndexOf(“locate”, 15);

</script>

</body>

</html>

Output

JavaScript String Methods

The lastIndexOf() method accepts a second parameter as the starting position for the search.

Remember that the lastIndexOf() method searches backwards, so position 15 means start the search at position 15, and search to the beginning.

Position 15 is position 15 from the beginning.

7

JavaScript String search()

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Methods</h2>

<p>The search() method returns the position of the first occurrence of a specified text in a string:</p>

<p id=”demo”></p>

<script>

let str = “Please locate where ‘locate’ occurs!”;

document.getElementById(“demo”).innerHTML = str.search(“locate”);

</script>

</body>

</html>

Output

JavaScript String Methods

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

7

JavaScript 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”:

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Search</h2>

<p>Search a string for “ain”:</p>

<p id=”demo”></p>

<script>

let text = “The rain in SPAIN stays mainly in the plain”;

document.getElementById(“demo”).innerHTML = text.match(/ain/g);

</script>

</body>

</html>

Output

JavaScript String Search

Search a string for "ain":

ain,ain,ain

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”:

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Search</h2>

<p>Perform a global, case-insensitive search for “ain”:</p>

<p id=”demo”></p>

<script>

let text = “The rain in SPAIN stays mainly in the plain”;

document.getElementById(“demo”).innerHTML = text.match(/ain/gi);

</script>

</body>

</html>

Output

JavaScript String Search

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

ain,AIN,ain,ain

JavaScript String includes()

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Search</h2>

<p>Check if a string includes “world”:</p>

<p id=”demo”></p>

<p>The includes() method is not supported in Internet Explorer.</p>

<script>

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

document.getElementById(“demo”).innerHTML = text.includes(“world”);

</script>

</body>

</html>

Output

JavaScript String Search

Check if a string includes "world":

true

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

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:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript String Search</h2>

<p>Check if a string includes “world”:</p>

<p id=”demo”></p>

<p>The includes() method is not supported in Internet Explorer.</p>

<script>

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

document.getElementById(“demo”).innerHTML = text.includes(“world”, 12);

</script>

</body>

</html>

Output

JavaScript String Search

Check if a string includes "world":

false

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

JavaScript String startsWith()

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

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Strings</h2>

<p>Check if a string starts with “Hello”:</p>

<p id=”demo”></p>

<p>The startsWith() method is not supported in Internet Explorer.</p>

<script>

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

document.getElementById(“demo”).innerHTML = text.startsWith(“Hello”);

</script>

</body>

</html>

Output

JavaScript Strings

Check if a string starts with "Hello":

true

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

Syntax

string.startsWith(searchvalue, start)

Example

<!DOCTYPE html>

<html>

<body

<h2>JavaScript Strings</h2>

<p>The startsWith() method.</p>

<p id=”demo”></p>

<p>The startsWith() method is not supported in Internet Explorer.</p>

<script>

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

document.getElementById(“demo”).innerHTML = text.startsWith(“world”, 6);

</script>

</body>

</html>

Output

JavaScript Strings

The startsWith() method.

true

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

JavaScript 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”:

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Strings</h2>

<p>Check in the 11 first characters of a string ends with “world”:</p>

<p id=”demo”></p>

<p>The endsWith() method is not supported in Internet Explorer.</p>

<script>

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

document.getElementById(“demo”).innerHTML = text.endsWith(“world”, 11);

</script>

</body>

</html>

Output

JavaScript Strings

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

true

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


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