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Check If a String Contains a Substring in JavaScript
JavaScript provides us with different methods to check whether a string contains a substring or not. In this article, we use the following three methods for this purpose-
String search() method
String indexOf() method
String includes() method
Let’s explore in detail each method.
1. String search() method
The string search method can be used to search a text (using regular expression) in a string.
It matches the string against a regular expression and returns the index (position) of the first match.
It returns -1 if no match is found. It’s case-sensitive.
The string search() method is an ES1 feature. It is fully supported in all browsers.
Syntax
string.search(searchValue)
searchValue is a regular expression or a string (will be converted to a regular expression).
Example
You can try to run the following code to check whether the string “Tutorialspoint: Free Video Tutorial” contains a substring “point” in or not. We use string search() method.
<html>
<head>
<title>JavaScript String search() Method</title>
</head>
<body>
<script>
var re = "point";
var str = "Tutorialspoint: Free Video Tutorials";
if ( str.search(re) == -1 ) {
document.write("Does not contain Point" );
} else {
document.write("Contains Point!" );
}
</script>
</body>
</html>
Output
This will produce the following result -
Contains Point!"
2. String indexOf() method
The string indexOf() method can be used to check if a string contains a substring or not.
It returns the position of the first occurrence of a value (substring) in the string otherwise it returns -1 if the value is not found.
The string indexOf() method is case-sensitive. This method cannot search against a regular expression.
The string indexOf() method is an ES1 feature. It is fully supported in all browsers.
Syntax
string.indexOf(searchvalue, start)
Parameters
searchValue - is a string to search for.
Start - the index to start from (default is 0). It’s an optional parameter.
Example
In the example program below, we use string indexOf() method to check whether the string “Tutorialspoint: Free Video Tutorial” contains a substring “point” or not.
<html>
<head>
<title>JavaScript String search() Method</title>
</head>
<body>
<script>
var re = "point";
var str = "Tutorialspoint: Free Video Tutorials";
if ( str.indexOf(re) !== -1) {
document.write("Contains "+ re );
} else {
document.write("Does not contain "+ re);
}
</script>
</body>
</html>
Output
This will produce the following result -
Contains point
3. String includes() method
The string includes() method is introduced in ES6. It is supported in all modern browsers.
It returns true if a string contains a specified substring otherwise it returns false.
The includes() method is case sensitive. This method is not supported in Internet Explorer 11 (or earlier).
Syntax
string.includes(searchvalue, start)
Parameters
searchValue - is a string to search for.
Start - the index to start from (default is 0). It’s an optional parameter.
Example
In the example program below, we use the string includes() method to check whether the string “Tutorialspoint: Simply Easy Learning” contains a substring “JavaScript” or not.
<html>
<head>
<title>JavaScript String search() Method</title>
</head>
<body>
<script>
var re = "JavaScript";
var str = "Tutorialspoint: Simply Easy Learning";
if ( str.includes(re)) {
document.write("Contains "+ re );
} else {
document.write("Does not contain "+ re);
}
</script>
</body>
</html>
Output
This will produce the following result -
Does not contain JavaScript
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