I am having trouble forming regular expression containing all alphanumeric characters and one or two specific characters, such us _ or -.

This expression works for all alphanumeric characters /^[0-9a-zA-Z]+$/.

I am having trouble forming regular expression containing all alphanumeric characters and one or two specific characters, such us _ or -.

This expression works for all alphanumeric characters /^[0-9a-zA-Z]+$/.

• javascript
• regex
• alphanumeric

• You need a regex to find another regex? – Gabber Commented Aug 29, 2012 at 10:34

2 Answers 2

Try this:

/^[0-9a-zA-Z-_]+$/

If you enter the dash sign "-" at a position where it can be interpreted as a range such as _- it would mean any characters matching _ or above in the ascii table.

Add the special characters inside the square brackets

/^[0-9a-zA-Z_-]+$/

To use this regex in javascript use this code (yourPhrase is the string you check vs the regexp)

var rexp = /^[0-9a-zA-Z_-]+$/
if(rexp.test(yourPhrase)){
    //code to handle the test
}