How to tell if a string contains a certain character in JavaScript?

javascript string
Vivian River picture Vivian River · Dec 14, 2010 · Viewed 758.6k times · Source

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?

Answer

kemiller2002 picture kemiller2002 · Dec 14, 2010

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:

http://www.regular-expressions.info/javascript.html

Alpha Numeric Regular Expression

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