regular expression on javascript

**jeffap** · 08-06-2012, 12:19 AM

i want to validate an input value using the following function which included a regular expression. And my criteria of the value is:

1) any keyword with characters 'a-z', 'A-Z', '0-9', '-', '_', but the first character of the keyword must be without hyphen and underscore;

2) at most 3 keywords in the html input, with one comma separating each other

PHP Code:


function checkKeywords(str){
    var re=/^([a-zA-Z0-9]{1})([a-zA-Z0-9-_]+)(([\,]{1})([a-zA-Z0-9]{1})([a-zA-Z0-9-_]+))?(([\,]{1})([a-zA-Z0-9]{1})([a-zA-Z0-9-_]+))?$/;
    return re.test(str);
}

if(doucment.form.keywords.value !="" && !checkKeywords(doucment.form.keywords.value)){
    return false;
}

PHP Code:


html code:
<form onSubmit="checkKeywords();">
<input type="text" name="keywords" id="keywords" value="<?php echo stripslashes(htmlentities($_POST['keywords'])); ?>" />
</form>

the problem should come from the wrong regular expression. I am sorry for the long clumsy code because i wrote it all by myself

Your help is very much appreciated

**bionoid** · 08-06-2012, 02:20 AM

It's a little longer, but this is what I would do:

Code:

function checkKeywords(str)
{
	var kw = String(str).split(','), i;
	if (kw.length > 3) {
		alert('Too many keywords!');
		return false;
	} else {
		for (i = 0; i < kw.length; ++i) {
			if (!(/^[a-z0-9]{1}[\w\-]*$/i).test(kw[i])) {
				alert('Invalid keyword: ' + kw[i]);
				return false;
			}
		}
	}
	return true;
}

Don't forget to also return the result of the check to your form:

Code:

<form onSubmit="return checkKeywords(this.keywords.value);">
<input type="text" name="keywords" id="keywords" value="<?php echo stripslashes(htmlentities($_POST['keywords'])); ?>" />
</form>

**jeffap** · 08-06-2012, 05:27 AM

hi bionoid, your code is neat, clean and easy to understand, much better than mine

i have a question here, when you define var kw

var kw = String(str).split(','), i;

can javascript recognize "String"?

i tried put it in my .js but it does not work

i actually put it in a "check" function for all input, like:

PHP Code:


function check(form){
    if(bla bla bla){
        bla bla bla;
        return false;
    }
    if(form.keywords.value !=""){
        ***your function???***
    }
    return true;
}

html:

<form onSubmit="return check(this);">
.
.
.
    <input name="keywords">
.
.
.
</form>

ps: i want to check out some fundamental javascript rules because i think i always make mistakes and waste lots of time to fix them. any simple (for dummy) website for me

**bionoid** · 08-06-2012, 05:35 AM

If you can post all the code/html you are working on, or if you have it online, I could see where the problem is.

This is the code I used to experiment with your question:

Code:

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="utf-8" />
		<title>Check Input</title>

		<script type="text/javascript">

			function checkKeywords(str)
			{
				var kw = String(str).split(','), i;
				if (kw.length > 3) {
					alert('Too many keywords!');
					return false;
				} else {
					for (i = 0; i < kw.length; ++i) {
						if (!(/^[a-z0-9]{1}[\w\-]*$/i).test(kw[i])) {
							alert('Invalid keyword: ' + kw[i]);
							return false;
						}
					}
				}
				return true;
			}

		</script>

	</head>
	<body>

		<form onSubmit="return checkKeywords(this.keywords.value);">
			<input type="text" name="keywords" id="keywords" value="123,-456,789" />
			<input type="submit" />
		</form>

	</body>
</html>

**jeffap** · 08-06-2012, 09:39 AM

the whole php and js code are pretty long so i will put what it is relevant

PHP Code:


<html>
<head>
        <script type="text/javascript" src="checksell.js"></script>        
</head>
<body>
    <form action="verify.php" method="post" target="_self" onSubmit="return checkForm(this);">
        <input type="text" name="keywords" value="<?php echo stripslashes(htmlentities($_POST['keywords'])); ?>" />
        <input name="submit" type="submit" value="submit" />
</form>
</body>
</html>

PHP Code:


//checksell.js

function checkForm(form){
    if(form.keywords.value !=""){
        function checkKeywords(str){
            var kw = String(str).split(','), i;
            if (kw.length > 3){
                alert('too many keywords');
                form.keywords.focus();            
                return false;
            }else{
                for (i = 0; i < kw.length; ++i) {
                    if (!(/^[a-z0-9\u4e00-\u9fa5]{1}[\w\-\u4e00-\u9fa5]*$/i).test(kw[i])){
                        alert('invalid keywords');
                        form.keywords.focus();                        
                        return false;
                    }
                }
            }
        }
    }
    return true;
}

**bionoid** · 08-06-2012, 10:37 AM

Try this:

checksell.js

Code:

function checkForm(form)
{
	var e = form.keywords, kw, i;
	if (e.value !== '') {
		kw = String(e.value).split(',');
		if (kw.length > 3) {
			alert('too many keywords'); e.focus(); return false;
		} else {
			for (i = 0; i < kw.length; ++i) {
				if (!(/^[a-z0-9\u4e00-\u9fa5]{1}[\w\-\u4e00-\u9fa5]*$/i).test(kw[i])) {
					alert('invalid keywords'); e.focus(); return false;
				}
			}
		}
	} else {
		alert('please specify a keyword'); e.focus(); return false;
	}
	return true;
}

**jeffap** · 08-06-2012, 11:54 AM

awesome it works

thank you very much for your help!

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