New RegExp() JavaScript Question

[wildgoosespeeder]

For my Multi-Colored Display Names code, what's the point of "$" for this line?

if(a[href].href.match(new RegExp("action=viewprofile&user=" + memberscolors[loop][0] + "$")))

[James [a_leon]]

The $ indicates that it's the end of the string.

So let's say you have two members, one with a username of "matt" and one with a username of "matthew". If you didn't have the $ there, and you wanted to give a colored display name to matt, it would also match matthew because "matt" is contained in it.

[wildgoosespeeder]

So if there is anything else where that $ is, it doesn't count it and makes that expression false?

[James [a_leon]]

Correct. If you take it out, then it matches any username that starts with "matt". If you leave it there, it matches only what you've told it to.

One thing you could do, is on a test board, create two users called "user" and "user1". Apply the code to "user", but take out the $, and you should see it affect both accounts. I find actually playing with the modification as opposed to reading about it helps me.

[wildgoosespeeder]

Does $ work also like:

new RegExp("$" + loop)
so if loop = "att" and we have att and matt, it wouldn't work for matt?

[Peter]

Aug 19, 2010 21:11:59 GMT -8 wildgoosespeeder said:

Does $ work also like:

new RegExp("$" + loop)
so if loop = "att" and we have att and matt, it wouldn't work for matt?

Nope, you would need a different metacharacter, you will need to use ^ to match the start of the line.

I recommend doing what James suggested, create a few users and just modify the expression, that way you will have a much better understanding of them.

[Charles Stover]

$ means the end of the line. ^ means the beginning of the line.

/test/ (contains test) matches
test
atest
testa
atesta

/^test/ (starts with test) matches
test
testa

/test$/ (ends with test) matches
test
atest

/^test$/ (starts and ends with test) matches
test

[wildgoosespeeder]

Aug 20, 2010 4:21:17 GMT -8 Charles Stover said:

/^test$/ (starts and ends with test) matches
test

OK got all that but wouldn't the thing I quoted be the same thing as "test"? Meaning:

word.match(/^test$/)

and

word == "test"

are the same thing?

[Aaron]

In a conditional, as posted, the two are equivalent, yes. The advantage is brevity.

if(word.match(/^(user|user2|user4|user7)$/)

if(word == "user" || word == "user2" || word == "user4" || word == "user7")

[James [a_leon]]

Aug 20, 2010 10:41:39 GMT -8 wildgoosespeeder said:

Aug 20, 2010 4:21:17 GMT -8 Charles Stover said:

/^test$/ (starts and ends with test) matches
test

OK got all that but wouldn't the thing I quoted be the same thing as "test"? Meaning:

word.match(/^test$/)

and

word == "test"

are the same thing?

Yes, but an advantage to using word.match(/^test$/) is that you can add flags to make it so it'll match any casing. So you could match Test, TEST, TeST, etc, instead of just "test". That'd be word.match(/^test$/i)

Now, you could match the same using word == "test", but you'd have to do it like this:
word.toLowerCase () == "test"

I just prefer to use the .match, allows for matching variable strings better.

And of course what Aaron said, I just felt that was important enough to note.

[wildgoosespeeder]

I know what "g" and "i" do. The "g" is for finding all cases where the RegExp is true and "i" means case insensitive.

Yup I understand completely!

Another question. So if I wanted to search for ^ or $, I'd do /\^/ or /\$/?

[Jordan]

Aug 20, 2010 17:33:45 GMT -8 wildgoosespeeder said:

I know what "g" and "i" do. The "g" is for finding all cases where the RegExp is true and "i" means case insensitive.

Yup I understand completely!

Another question. So if I wanted to search for ^ or $, I'd do /\^/ or /\$/?

Yes, but don't take our word for it, try it yourself.