Javascript – How to tell if a string contains a certain character in JavaScript


I have a page with a textbox where a user is supposed to enter a 24 character (letters and numbers, case insensitive) registration code. I used maxlength to limit the user to entering 24 characters.

The registration codes are typically given as groups of characters separated by dashes, but I would like for the user to enter the codes without the dashes.

How can I write my JavaScript code without jQuery to check that a given string that the user inputs does not contain dashes, or better yet, only contains alphanumeric characters?

Best Solution

To find "hello" in your_string

if (your_string.indexOf('hello') > -1)
  alert("hello found inside your_string");

For the alpha numeric you can use a regular expression:

Alpha Numeric Regular Expression