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Javascript regex match and get values from string

I've got a string of text which can have specific tags in it.
Example: var string = '<pause 4>This is a line of text.</pause><pause 7>This is the next part of the text.</pause>';
What I'm trying to do is do a regex match against the <pause #></pause> tag.
For each tags found, in this case it's <pause 4></pause> and <pause 7></pause>. What I want is to grab the value 4 and 7, and the string length divided by for the string in between the <pause #>...</pause> tags.
What I have for now is not much.
But I cant figure out how to grab all the cases, then loop through each one and grab the values I'm looking for.
My function for this looks like this for now, it's not much:
/**
* checkTags(string)
* Just check for tags, and add them
* to the proper arrays for drawing later on
* #return string
*/
function checkTags(string) {
// Regular expresions we will use
var regex = {
pause: /<pause (.*?)>(.*?)<\/pause>/g
}
var matchedPauses = string.match(regex.pause);
// For each match
// Grab the pause seconds <pause SECONDS>
// Grab the length of the string divided by 2 "string.length/2" between the <pause></pause> tags
// Push the values to "pauses" [seconds, string.length/2]
// Remove the tags from the original string variable
return string;
}
If anyone can explain my how I could do this I would be very thankful! :)

match(/.../g) doesn't save subgroups, you're going to need exec or replace to do that. Here's an example of a replace-based helper function to get all matches:
function matchAll(re, str) {
var matches = [];
str.replace(re, function() {
matches.push([...arguments]);
});
return matches;
}
var string = '<pause 4>This is a line of text.</pause><pause 7>This is the next part of the text.</pause>';
var re = /<pause (\d+)>(.+?)<\/pause>/g;
console.log(matchAll(re, string))
Since you're removing tags anyways, you can also use replace directly.

You need to make a loop to find all matched groups of your RegExp pattern in the text.
The matched group is an array containing the original text, the matched value and the match text.
var str = '<pause 4>This is a line of text.</pause><pause 7>This is the next part of the text.</pause>';
function checkTags(str) {
// Regular expresions we will use
var regex = {
pause: /<pause (.*?)>(.*?)\<\/pause>/g
}
var matches = [];
while(matchedPauses = regex.pause.exec(str)) {
matches.push([matchedPauses[1], matchedPauses[2].length /2]);
};
return matches;
}
console.log(checkTags(str));

As a start point since you have not much so far you could try this one
/<pause [0-9]+>.*<\/pause>/g
Than to get the number out there you match again using
/[0-9]+>/g
To get rid of the last sign >
str = str.slice(0, -1);

Keeping only part of a regex match

I need to search for a word in text. For this I used this regex:
var re =/duration='\d+'/ig;
var i = text.match(re);
This gives me an array of matches like "duration='300'", "duration='400'",...
I need to get only numbers. without duration=''

You can use a capturing group:
var re = /duration='(\d+)'/ig;
var match = re.exec(text);
while (match != null) {
// matched text: match[1]
match = re.exec(text);
}

Tim's answer works well (and I'm not sure why the OP says it is not what he/she wants). That said, here is another way to do it using the String.replace() method with a callback function replacement value:
function getDurations(text) {
var re =/duration='(\d+)'/ig;
var i = [];
text.replace(re, function(m0, m1){i.push(m1); return '';});
return i;
}
Note that this technique requires no loop and is quite efficient getting the job done in a single statement.

group parts of a string into an array element

If I have a string... abcdefghi
and I want to use regex to load every elemnent into an array but I want to be able to stick anything connected by plus sign into the same element... how to do that?
var mystring = "abc+d+efghi"
output array ["a","b","cde","f","g","h","i"]

One way to do it:
var re = /([^+])(?:\+[^+])*/g;
var str = 'abcd+e+fghi';
var a = str.match(re).map(function (s) { return s.replace(/\+/g, ''); });
console.log(a);
The value of a[3] should now be 'def'.
http://jsfiddle.net/rbFwR/2

You can use this expression, to produce [a][b][c+d+e][f][g][h][i].
mystring.split ("(.\+)*.")
Next, replace any + characters with empty on the resulting list.

mystring.split("\\+")
Click here for more information.

Why does this jQuery code not work?

Why doesn't the following jQuery code work?
$(function() {
var regex = /\?fb=[0-9]+/g;
var input = window.location.href;
var scrape = input.match(regex); // returns ?fb=4
var numeral = /\?fb=/g;
scrape.replace(numeral,'');
alert(scrape); // Should alert the number?
});
Basically I have a link like this:
http://foo.com/?fb=4
How do I first locate the ?fb=4 and then retrieve the number only?

Consider using the following code instead:
$(function() {
var matches = window.location.href.match(/\?fb=([0-9]+)/i);
if (matches) {
var number = matches[1];
alert(number); // will alert 4!
}
});
Test an example of it here: http://jsfiddle.net/GLAXS/
The regular expression is only slightly modified from what you provided. The global flag was removed, as you're not going to have multiple fb='s to match (otherwise your URL will be invalid!). The case insensitive flag flag was added to match FB= as well as fb=.
The number is wrapped in curly brackets to denote a capturing group which is the magic which allows us to use match.
If match matches the regular expression we specify, it'll return the matched string in the first array element. The remaining elements contain the value of each capturing group we define.
In our running example, the string "?fb=4" is matched and so is the first value of the returned array. The only capturing group we have defined is the number matcher; which is why 4 is contained in the second element.

If you all you need is to grab the value of fb, just use capturing parenthesis:
var regex = /\?fb=([0-9]+)/g;
var input = window.location.href;
var tokens = regex.exec(input);
if (tokens) { // there's a match
alert(tokens[1]); // grab first captured token
}

So, you want to feed a querystring and then get its value based on parameters?
I had had half a mind to offer Get query string values in JavaScript.
But then I saw a small kid abusing a much respectful Stack Overflow answer.
// Revised, cooler.
function getParameterByName(name) {
var match = RegExp('[?&]' + name + '=([^&]*)')
.exec(window.location.search);
return match ?
decodeURIComponent(match[1].replace(/\+/g, ' '))
: null;
}
And while you are at it, just call the function like this.
getParameterByName("fb")

How about using the following function to read the query string parameter in JavaScript:
function getQuerystring(key, default_) {
if (default_==null)
default_="";
key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
var regex = new RegExp("[\\?&]"+key+"=([^&#]*)");
var qs = regex.exec(window.location.href);
if(qs == null)
return default_;
else
return qs[1];
}
and then:
alert(getQuerystring('fb'));

If you are new to Regex, why not try Program that illustrates the ins and outs of Regular Expressions

Extracting 1 or more hyperlinks from paragraph text in Javascript using Regular Expression

Sorry to bother you guys again, but here's my dilemma.
There must be a "better" regular expression to identify HTML link from a paragraph text (there can be more than 1 html links in the text). How do I extract all the link and anchor it in javascript?
My attempt (in javascript) is like this:
var urlPattern = "(https?|ftp)://(www\\.)?(((([a-zA-Z0-9.-]+\\.){1,}[a-zA-Z]{2,4}|localhost))|((\\d{1,3}\\.){3}(\\d{1,3})))(:(\\d+))?(/([a-zA-Z0-9-._~!$&'()*+,;=:#/]|%[0-9A-F]{2})*)?(\\?([a-zA-Z0-9-._~!$&'()*+,;=:/?#]|%[0-9A-F]{2})*)?(#([a-zA-Z0-9._-]|%[0-9A-F]{2})*)?";
function extractURLs(s) {
return s.match(new RegExp(urlPattern));
}
//s is of type String
//For testing...
var text = "Check this video out http://ww w.youtube.com/watch?v=y3U3R3b1dOg or http://www.youtube.com/watch?v=sX6Vm0MoPCY";
alert(extractURLs(text));
(spaces on hyperlink has been deliberately added here to allow posting of question in SO).
Result: I only get the 1st hyperlink and not the second one....
Has anybody done something similar or better that I can utilize?
Thanks in advance.

Use the "g" modifier:
function extractURLs(s) {
return s.match(new RegExp(urlPattern, "g"));
}

var urlPattern = "(https?|ftp)://(www\\.)?(((([a-zA-Z0-9.-]+\\.){1,}[a-zA-Z]{2,4}|localhost))|((\\d{1,3}\\.){3}(\\d{1,3})))(:(\\d+))?(/([a-zA-Z0-9-._~!$&'()*+,;=:#/]|%[0-9A-F]{2})*)?(\\?([a-zA-Z0-9-._~!$&'()*+,;=:/?#]|%[0-9A-F]{2})*)?(#([a-zA-Z0-9._-]|%[0-9A-F]{2})*)?";
function extractURLs(s) {
return s.match(new RegExp(urlPattern));
}
var text = "Check this video out http://www.youtube.com/watch?v=y3U3R3b1dOg or http://www.youtube.com/watch?v=sX6Vm0MoPCY";
var results = extractURLs(text);
alert(extractURLs(results[0] + ", " + results[1]));

It is better to write it as,
var urlPattern = /(https?|ftp)://(www\\.)?(((([a-zA-Z0-9.-]+\\.){1,}[a-zA-Z]{2,4}|localhost))|((\\d{1,3}\\.){3}(\\d{1,3})))(:(\\d+))?(/([a-zA-Z0-9-._~!$&'()*+,;=:#/]|%[0-9A-F]{2})*)?(\\?([a-zA-Z0-9-._~!$&'()*+,;=:/?#]|%[0-9A-F]{2})*)?(#([a-zA-Z0-9._-]|%[0-9A-F]{2})*)?/g;
function extractURLs(s) {
return s.match(urlPattern);
}
Here urlPattern is pre-compiled, rather than compiling the RegEx everytime the function is called, hence results in petter performance.