Let\u2019s say you have a string and you want to check if it contains a specific word, character or substring. In this article, you will learn about different ways in which you can perform the check using JavaScript. Here are a few variables that we are going to use:<\/p>\n
JavaScript<\/p>\n
var theString = \"I have been looking for Sam.\";\nvar theWord = \"look\";\nvar theCharacter = \"I\";\nvar theSubstring = \"for Sam\";<\/code><\/pre>\nUsing String.indexOf() to Check if String Contains Substring<\/h2>\n
The fastest way to check if a string contains a particular word or substring is with the help of String.indexOf()<\/a> method. This method returns the index of the first occurrence of the specified substring inside the calling String object. If the substring or word is not found, it returns -1. <\/p>\nThis means that you can compare the value returned by the indexOf()<\/code> method to see if it is equal to -1. If the value is not -1, the calling string contains the substring we are looking for.<\/p>\nJavaScript<\/p>\n
var theString = \"I have been looking for Sam.\";\nvar theWord = \"looking\";\nvar theCharacter = \"I\";\nvar theSubstring = \"for Sam\";\n\n\n\/\/ Output \u2014 The word \"looking\" exists in given string.\nif (theString.indexOf(theWord) !== -1) {\n console.log('The word \"' + theWord + '\" exists in given string.');\n}\n\n\/\/ Output \u2014 The character \"I\" exists in given string.\nif (theString.indexOf(theCharacter) !== -1) {\n console.log('The character \"' + theCharacter + '\" exists in given string.');\n}\n\n\/\/ Output \u2014 The substring \"for Sam\" exists in given string.\nif (theString.indexOf(theSubstring) !== -1) {\n console.log('The substring \"' + theSubstring + '\" exists in given string.');\n}<\/code><\/pre>\nYou are not limited to the strict inequality operator (!==<\/code>), you can also use > -1<\/code>. This is because if the word or substring exists in the given string, the index returned would always be greater than or equal to 0. However, remember that the greater than operator (><\/code>) is slower than the strict inequality operator (!==<\/code>).<\/p>\nOne important point that should be kept in mind is that if you meant to search exactly for \u201clook\u201d in the above string, the method would still return an index greater than -1 because \u201clooking\u201d exists in the string. If you are looking for exact matches, you will have to be extra careful.<\/p>\n
This method is case-sensitive so you would have got -1 if you searched for \u201cLooking\u201d instead of \u201clooking\u201d.<\/p>\n
Using String.includes() to Check if String Contains Substring<\/h2>\n
You can also use the String.includes()<\/a> to check if a string contains another word, character or substring. This method will return TRUE if the substring can be found within the main string and FALSE otherwise.<\/p>\nJavaScript<\/p>\n
var theString = \"I have been looking for Sam.\";\nvar theWord = \"looking\";\nvar theCharacter = \"I\";\nvar theSubstring = \"for Sam\";\n\n\/\/ Output \u2014 The word \"looking\" exists in given string.\nif (theString.includes(theWord)) {\n console.log('The word \"' + theWord + '\" exists in given string.');\n}\n\n\/\/ Output \u2014 The character \"I\" exists in given string.\nif (theString.includes(theCharacter)) {\n console.log('The character \"' + theCharacter + '\" exists in given string.');\n}\n\n\/\/ Output \u2014 The substring \"for Sam\" exists in given string.\nif (theString.includes(theSubstring)) {\n console.log('The substring \"' + theSubstring + '\" exists in given string.');\n}<\/code><\/pre>\nJust like String.indexOf()<\/code>, this method is also case-sensitive. One major issue with this method is that the browser support for String.includes()<\/code> is not as good as String.indexOf()<\/code>. If you don\u2019t care about the browser support for Internet Explorer, you can use String.includes()<\/code> without second thought.<\/p>\nUsing String.search() to Check if String Contains Substring<\/h2>\n