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. How to check if a String contains substring or a word using javaScript const str = 'Bread and Milk' Ĭonsole.log(str.toLowerCase().includes(char.toLowerCase())) // true

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