jQuery: Check if special characters exists in string

Question

I know this question is asked more often here on Stack, but I can't seem to get a straight answer out of the questions already posted.

I need to check if all special characters (except -) are in a string, if so, then give the user an alert.

What I have so far is this:

if($('#Search').val().indexOf('@') == -1 || $('#Search').val().indexOf('#') == -1 || $('#Search').val().indexOf('$') == -1 || $('#Search').val().indexOf('%') == -1 || $('#Search').val().indexOf('^') == -1 || $('#Search').val().indexOf('&') == -1 || $('#Search').val().indexOf('*') == -1 || $('#Search').val().indexOf('(') == -1 || $('#Search').val().indexOf(')') == -1 || $('#Search').val().indexOf('_') == -1 || $('#Search').val().indexOf('\'') == -1 || $('#Search').val().indexOf('\"') == -1 || $('#Search').val().indexOf('\\') == -1 || $('#Search').val().indexOf('|') == -1 || $('#Search').val().indexOf('?') == -1 || $('#Search').val().indexOf('/') == -1 || $('#Search').val().indexOf(':') == -1 || $('#Search').val().indexOf(';') == -1 || $('#Search').val().indexOf('!') == -1 || $('#Search').val().indexOf('~') == -1 || $('#Search').val().indexOf('`') == -1 || $('#Search').val().indexOf(',') == -1 || $('#Search').val().indexOf('.') == -1 || $('#Search').val().indexOf('<') == -1 || $('#Search').val().indexOf('>') == -1 || $('#Search').val().indexOf('{') == -1 || $('#Search').val().indexOf('}') == -1 || $('#Search').val().indexOf('[') == -1 || $('#Search').val().indexOf(']') == -1 || $('#Search').val().indexOf('+') == -1 || $('#Search').val().indexOf('=') == -1) { // Code that needs to execute when none of the above is in the string } else { alert('Your search string contains illegal characters.'); }

But this doesn't seem to work. Can anyone help me on this matter?

You need to use a regular expression here instead of a bazillion separate conditions. And you definitely have to say how exactly it "doesn't seem to work". — Jon
– Jon, Commented Dec 12, 2012 at 12:48
See this may be help you stackoverflow.com/questions/10505772/… — Hkachhia
– Hkachhia, Commented Dec 12, 2012 at 12:53

bfavaretto · Accepted Answer · 2012-12-12 13:47:47Z

101

If you really want to check for all those special characters, it's easier to use a regular expression:

var str = $('#Search').val(); if(/^[a-zA-Z0-9- ]*$/.test(str) == false) { alert('Your search string contains illegal characters.'); }

The above will only allow strings consisting entirely of characters on the ranges a-z, A-Z, 0-9, plus the hyphen an space characters. A string containing any other character will cause the alert.

edited Dec 12, 2012 at 13:47

answered Dec 12, 2012 at 12:50

bfavaretto

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7 Comments

bfavaretto Over a year ago

Added a short explanation. The downside is that it won't allow international characters like é and ñ, but if you don't need to allow them I believe it's the way to go.

Guido Visser Over a year ago

It works, even with the international characters ;) Thanks again!

Marvin Saldinger Over a year ago

This fails for international characters (chinese, arabic etc). I wouldn't use it. It doesn't look for special characters like anton's example.

Alston Over a year ago

Why don't we write /[^a-zA-Z0-9- ]*$/ instead of /^[a-zA-Z0-9- ]*$/?

bfavaretto Over a year ago

@Stallman The meaning is different. Inside the brackets, the ^ negates the list instead of defining the beginning of the string.

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Thilina Sampath · Accepted Answer · 2015-12-08 05:13:35Z

var specialChars = "<>@!#$%^&*()_+[]{}?:;|'\"\\,./~`-=" var check = function(string){ for(i = 0; i < specialChars.length;i++){ if(string.indexOf(specialChars[i]) > -1){ return true } } return false; } if(check($('#Search').val()) == false){ // Code that needs to execute when none of the above is in the string }else{ alert('Your search string contains illegal characters.'); }

Jay Blanchard · Accepted Answer · 2012-12-12 13:24:54Z

You could also use the whitelist method -

var str = $('#Search').val(); var regex = /[^\w\s]/gi; if(regex.test(str) == true) { alert('Your search string contains illegal characters.'); }

The regex in this example is digits, word characters, underscores (\w) and whitespace (\s). The caret (^) indicates that we are to look for everything that is not in our regex, so look for things that are not word characters, underscores, digits and whitespace.

This fails for international characters(chinese, arabic etc).I wouldn't use it.
== true? Wouldn't if(regex.test(str)) { [...] } suffice?
Of course it would @scniro. I just put the entire equation for clarity sake.

JJJ · Accepted Answer · 2012-12-12 12:49:20Z

2

You are checking whether the string contains all illegal characters. Change the ||s to &&s.

answered Dec 12, 2012 at 12:49

JJJ

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