JavaScript RegExp \b and \B Metacharacter

The regex "\b" shows the available start or end of the character in the input string in JavaScript. The regex "\b" shows the character's unavailable start or end in the JavaScript input string. We can test, search, and match the arability of the required character in the string.

Syntaxes

JavaScript "\b" regex syntax

The syntax is used to show available characters at the start of the string.

The syntax shows the available character at the end of the string.

JavaScript "\B" regex syntax

The syntax shows an unavailable character at the start of the string.

The syntax shows the not available character at the end of the string.

Examples

JavaScript "\b" regex Examples

The examples show the availability of the character at the start or end of the string.

Example1

The example shows the availability of the required character at the start of the string.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \b Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \b Metacharacter 
</h3>
<h4> The search method with the "g" modifier get the position of the "po" character in the beginning.
</h4>
<div id = "regex_information"> </div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here ! </button>
</div>
<script>
//Get the position of the value at the start position
function display() {
let input_pattern = /\bpo/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java point';
//use regex search method for pattern 
var t1 = val1.search(input_pattern); 
var t2 = val2.search(input_pattern); 
var t3 = val3.search(input_pattern); 
//the output shows the availability of the value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java point : "+t3;
}
</script>
</body>
</html>

Output

The output shows the required character at the starting position.

$JavaScript RegExp \b and \B Metacharacter$

Example2

The example shows the availability of the required character at the end of the string.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \b Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \b Metacharacter 
</h3>
<h4> The search method with the "g" modifier gets the position of the "nt" character in the ending position.
</h4>
<div id = "regex_information"></div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here ! </button>
</div>
<script>
//Get the position of the value at the end position
function display() {
let input_pattern = /nt\b/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java Tpoint';
var t1 = val1.search(input_pattern); 
var t2 = val2.search(input_pattern); 
var t3 = val3.search(input_pattern); 
//the output shows the position of the value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java Tpoint : "+t3;
}
</script>
</body>
</html>

Output

The output shows the required character at the starting position.

$JavaScript RegExp \b and \B Metacharacter$

Example3

The example tests of the required character are available at the start of the string with the case-sensitive input value.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \b Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \b Metacharacter 
</h3>
<h4> The match method with the "g" modifier gets the position of the "java" character not in the beginning.
</h4>
<div id = "regex_information"> </div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here! </button>
</div>
<script>
//Get the value using the match method at the start position
function display() {
let input_pattern = /\bjava/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java point';
//use regex match method for pattern 
var t1 = val1.match(input_pattern); 
var t2 = val2.match(input_pattern); 
var t3 = val3.match(input_pattern); 
//the output shows the position of the value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java point : "+t3;
}
</script>
</body>
</html>

Output

The output shows the case-sensitive character of the beginning position.

$JavaScript RegExp \b and \B Metacharacter$

JavaScript "\B" regex Examples

The examples show no character availability at the start or end of the string.

Example1

The example shows the required character is unavailable at the start of the string.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \B Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \B Metacharacter 
</h3>
<h4> The search method with the "g" modifier gets the position of the "va" character, not in the ending position.
</h4>
<div id = "regex_information"></div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here ! </button>
</div>
<script>
function display() {
// use not available po value at the start of the position
let input_pattern = /\Bpo/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java point';
//use the search method for the input pattern 
var t1 = val1.search(input_pattern); 
var t2 = val2.search(input_pattern); 
var t3 = val3.search(input_pattern); 
//the output shows the not available position of the value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java point : "+t3;
}
</script>
</body>
</html>

Output

The output shows the required character, not at the beginning position.

$JavaScript RegExp \b and \B Metacharacter$

Example2

The example shows the not available required character at the end of the string. We can get the regular expression or required character to search for the end position.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \B Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \B Metacharacter 
</h3>
<h4> The search method with the "g" modifier gets the position of the "va" character, not in the ending position.
</h4>
<div id = "regex_information"></div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here ! </button>
</div>
<script>
function display() {
// use not available va value at the end of the position
let input_pattern = /va\B/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java point';
//use the search method for the input pattern 
var t1 = val1.search(input_pattern); 
var t2 = val2.search(input_pattern); 
var t3 = val3.search(input_pattern); 
//the output shows not available end position of the value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java point : "+t3;
}
</script>
</body>
</html>

Output

The output shows the required character, not the ending position.

$JavaScript RegExp \b and \B Metacharacter$

Example3

The example tests are not available for the required character at the start of the string with the case-sensitive input value. The lowercase data does not test the uppercase character of the string.

<!DOCTYPE html>
<html>
<head>
<title>
JavaScript RegExp \B Metacharacter
</title>
<style>
#demo1{
background-color: orange;
border: 1px solid black;
width: 350px;
}
</style>
</head>
<body>
<div id = "demo1">
<h3>
JavaScript RegExp \B Metacharacter 
</h3>
<h4> The match method with the "g" modifier gets the position of the "java" character not in the beginning.
</h4>
<div id = "regex_information"></div>
<!-- click the button to get the output -->
<button onclick = "display();"> Click Here ! </button>
</div>
<script>
function display() {
// use not available java value at the start of the position
let input_pattern = /\Bjava/g;
var val1 = 'Java T point';
var val2 = 'javatpoint';
var val3 = 'java point';
//use the match method for the input pattern 
var t1 = val1.match(input_pattern); 
var t2 = val2.match(input_pattern); 
var t3 = val3.match(input_pattern); 
//the output shows a null value 
var ele = document.getElementById("regex_information");
ele.innerHTML = "Java T point : "+t1+"<br> javatpoint: "+t2+" <br> java point : "+t3;
}
</script>
</body>
</html>

Output

The output shows the case-sensitive character of the beginning position.