Question

I’m using javascript’s inbuilt .test() function to test whether a string or regex matches. I took the regex from RegexLib, so I know that it matches the string it’s tested against (in this case [e-mail]), however it either returns false or nothing at all.

Here’s my code:

var string = "[e-mail]";
var pattern = [\w-]+@([\w-]+\.)+[\w-]+/i;
var match = pattern.test(string);

document.write(match);

When the regex is encased in quotes, the test returns false, when it’s not encased in anything, it returns nothing.

What I’ve tried so far:

• Simply using a single line, var match = '[\w-]+@([\w-]+\.)+[\w-]+/i'.test("[e-mail]");.
• Using both ' single quotes and " double quotes for both regex and string.
• Appending the regex with /i and /g.

I honestly don’t know what’s causing this issue, so any help would be great. It could be a complete rookie mistake, a forgotten syntax perhaps.

Here’s a link to the jsFiddle I made up for you to play around with if you think you’ve got some idea of how to fix this up: http://jsfiddle.net/wFhEJ/1/

Answer 1

You missed the opening slash for a regexp. The notation for a regexp is:

/regexp/flags

What happened with enclosing the regexp is that it became a string, and on jsFiddle String.prototype.test has been set by MooTools. MooTools seems to provide a String.prototype.test function, but it’s not the same as RegExp.prototype.test.

http://jsfiddle.net/wFhEJ/2/

var string = "[e-mail]";
var pattern = /[\w-]+@([\w-]+\.)+[\w-]+/i;
var match = pattern.test(string);

document.write(match);

Do note though that document.write is frowned upon. You might rather want document.body.appendChild(document.createTextNode(match)) or something alike.