It returns true if it finds a match, and false otherwise. The test() method searches the string for a match with the regex. One way to do this is with the RegExp test() method.
We can test the string against regex patterns to determine if it contains a particular character. This is why we compare the result of indexOf() with -1 to check if the character is in the string. If the value can’t be found, it returns -1.
The indexOf() method searches a string for a value and returns the index of the first occurrence of that value. For example: const str = 'Bread and Milk' Ĭonsole.log(str.indexOf(char1) > -1) // trueĬonsole.log(str.indexOf(char2) > -1) // false We call the indexOf() method on the string, passing the character as an argument. We can also use the indexOf() method to check if a string contains a particular character. const str = 'Bread and Milk' Ĭonsole.log(str.toLowerCase().includes(char.toLowerCase())) // true Ĭonsole.log(str.toLowerCase().includes("String".toLowerCase())) //trueĬonsole.log(str.toUpperCase().includes("String".To perform a case-insensitive check, convert both the string and the character to lowercase before calling includes() on the string. 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 Ĭonsole.log(str.includes("string", -3)) // true 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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