Using the includes() function you can check whether a string contains a substring in JavaScript. This method returns true if the string contains the characters, and false if not.
Usually, programmers would expect a String.contains() method, but there doesn’t exist in JS.
Syntax
string.includes(subString, start)Examples of the JavaScript string contains a substring
Let’s see multiple examples.
if the string contains
<!DOCTYPE html>
<html>
<head>
<script>
var str = "Hello world, welcome to the universe.";
var n = str.includes("world");
alert(n)
</script>
</head>
</html>Output:
Check javascript string contains a character
Let’s find “hello” in your_string using a indexOf() method in JS.
if (your_string.indexOf('hello') > -1)
{
alert("hello found inside your_string");
}The string contains case insensitive in JS
Add .toLowerCase() after referrer. This method turns the string into a lower case string. Then, use includes() function.
Check below code for it:-
if (referrer.toLowerCase().includes(someString.toLowerCase())) { ... }Do comment if you know other ways and have any doubts.
Note: The All JS Examples codes are tested on the Safari browser (Version 12.0.2) and Chrome.
OS: macOS 10.14 Mojave
Code: HTML 5 Version