at JavaScript, you can use the includes() method to check whether a string contains a substring . The includes() method returns a boolean value indicating whether the specified substring is present in the string.
The syntax for using the includes() method is as follows:
string.includes(substring);
Here, string is the string you want to search in, and substring is the substring you want to search for.
For example, let's say you have a string "Hello, world!" and you want to check whether it contains the substring "world". You can use the includes() method as follows:
var str = "Hello, world!";
var result = str.includes("world");
console.log(result); // Output: true
In this example, the includes() method returns true because the substring "world" is present in the string "Hello, world!".
Note that the includes() method is case-sensitive, so it will only match substrings that have the same case as the string being searched. If you want to perform a case-insensitive search, you can convert both the string and the substring to lowercase or uppercase using the toLowerCase() or toUpperCase() methods before calling includes().