Check a string for 1 to infinite repetitions of asterisk (*) using JavaScript regex o

anarchos78 · 08-25-2012, 11:35 PM

I am completely crap in regex and I need a little help with a task. How do I check a string for a single character repetition (in my case *) using javasctipt regex object. Specifically I need to check a string for 1 to n repetitions of * character. Notice that i need to check a string that contains only asterisks not any other character ex. not validate "tom***" or "**tom" or "*tom*" but "*" or "**" or "**n times". If the above case is true return true. Forgive my "noviceness".

With respect,

Tom

Greece

AndrewGSW · 08-26-2012, 12:10 AM

Code:

var expr = "**a";
var regex = /[^\*]/g;
if (!expr.length || expr == '') {
    alert('Empty string');
} else if (regex.test(expr)) {
    alert('Not just stars');
} else {
    alert('Just stars.');
}

seems to work

jmrker · 08-26-2012, 12:19 AM

Try ...

Code:

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8" />
<title> Untitled </title>
<script type="text/javascript">
function countStars(str) {
  alert(str+': '+/^\*+$/.test(str));
}
countStars('***')
countStars('*')

countStars('***tom');
countStars('tom**');
countStars('***tom**');
</script>

<style type="text/css">

</style>
</head>
<body>

</body>
</html>

AndrewGSW · 08-26-2012, 02:59 AM

I've slightly revised my example as I don't need to escape \ the asterisk as it is within a character class, and the global modifier is unnecessary with test():

Code:

var expr = "**";
var regex = /[^*]/;
if (!expr.length || expr == '') {
    alert('Empty string');
} else if (!regex.test(expr)) {
    alert('Just stars.');
}

The regex.test() expression essentially says "return true as soon as you find a character other than an asterisk, otherwise return false".

Philip M · 08-26-2012, 10:49 AM

Code:

<script type = "text/javascript">

var str = "***tom***";
if (/[^\*]/gi.test(str)) {
alert ("String contains characters other than asterisks");
}

var str = "*********";
var len = str.length;
alert ("There are " + len + " asterisks in your string")

</script>

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