This article will demonstrate the methods to write a JavaScript Program to check if a String contains any special characters. Any string that contains any character other than alphanumeric and space includes the special character. These special characters are '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '-', '+', '=', '{', '}', '[', ']', ':', ';', '"', '\'', '<', '>', ',', '.', '?', '/', '|', '\\', etc.
Example:
Input: Geeks$For$Geeks
Output: String contains special characters
Explanation: Input string contain '$' symbol
Input: Geeks For Geeks
Output: String doesnot contain any special character.
All Methods to Check if the String Contains any Special Characters
- Naive Method – Using Loops
- Using RegularExpression for Alphanumeric Characters
- Using RegEx for Special Characters
Approach 1: Naive Method – Using Loops
In this method, we will iterate the given string and check it for the ASCII values for the alphanumeric characters.
Example: In this example, we will use the for loop and check the ASCII value for every character.
Javascript
let str = "Geeks$for$Geeks"; console.log("Given String is: " + str) for (let i = 0; i < str.length; ++i) {     let ch = str.charCodeAt(i);     // console.log(ch);     if (         !(ch >= 65 && ch <= 90) && // A-Z         !(ch >= 97 && ch <= 122) && // a-z         !(ch >= 48 && ch <= 57) // 0-9     ) {         return console.log(             "String contains special characters"        );     } }   console.log("String does not contain any special character.") |
Given String is: Geeks$for$Geeks String contains special characters
Approach 2: Using RegEx for Alphanumeric Characters
In this method, we will create a regex for all the alphanumeric numbers like A-Z,a-z, and 0-9. and test the string with the same.
Example: In this example, we will use regex.test method to test the given string.
Javascript
const str = "Geeks$for$Geeks"; console.log("Given String is: " + str); const regex = /[^A-Za-z0-9]/; if (regex.test(str))     console.log("String contains special characters"); else    console.log(         "String does not contain any special character."    ); |
Given String is: Geeks$for$Geeks String contains special characters
Approach 3: Using RegEx for Special Characters
In this method, we will create a regex for all the special characters mention above and test the string with the same..
Example: In this example, we will use regex.test method to test the given string.
Javascript
const str = "neveropen"; console.log("Given String is: " + str); const regex = /[!@#$%^&*()\-+={}[\]:;"'<>,.?\/|\\]/; if (regex.test(str))     console.log("String contains special characters"); else     console.log(         "String does not contain any special character."     ); |
Given String is: neveropen String does not contain any special character.
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