Ideally, what we're looking for is a method with a name that matches our intention (determining if x contains y), and returns a simple true or false. That means that we can use it, but the clarity of the code suffers. In the event that no match is found, it will return -1. Its job is to return the index at which a given substring is found. While indexOf is often recommended as a simple way to test for the presence of a substring, that's not really its purpose. Ĭonsole.log(str.toLowerCase().includes("String".toLowerCase())) //trueĬonsole.log(str.toUpperCase().includes("String".Var philosophers = "Aquinas, Maimonedes, and Avicenna" var me = "Joshua" function printPhilosopherStatus ( person ) // Outputs: "Joshua is NOT a philosopher." printPhilosopherStatus ( me ) One of the ways to solve the syntax error is to convert the string and the substring to the same case before searching. However, it could not locate String in the string JavaScript string contains is easy, because it is case sensitive. The includes() method found the string substring in JavaScript string contains is easy. Will we locate the substring if we capitalize one of its characters?Ĭonsole.log(str.includes("String")) // false Yes, the str string contains the string substring.Įxample-4: Using various capitalization cases Here is an example using a negative index. Specifying a starting index less than the substring's leads to searching the substring throughout the entire string. But does it start at index 13?Įxample-3: Using a substring and a negative starting position It is true that the string substring starts at index 11 in the str string.
Ĭonsole.log(str.includes("string", 11)) // true We can also check whether the target substring is located at a specific index. It is true that the string JavaScript string contains is easy contains the string substring.Įxample-2: Using a substring and a starting position Now let's dive into practical examples of the includes() method.Ĭonst str = document.querySelector('p').textContentĬonsole.log(str.includes("string")) // true
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