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Is it possible to cut off the beginning of a string using regex?

I have a string which contains a path, such as
/foo/bar/baz/hello/world/bla.html
Now, I'd like to get everything from the second-last /, i.e. the result shall be
/world/bla.html
Is this possible using a regex? If so, how?
My current solution is to split the string into an array, and join its last two members again, but I'm sure that there is a better solution than this.

For example:
> '/foo/bar/baz/hello/world/bla.html'.replace(/.*(\/.*\/.*)/, "$1")
/world/bla.html

You can also do
str.split(/(?=\/)/g).slice(-2).join('')

> '/foo/bar/baz/hello/world/bla.html'.match(/(?:\/[^/]+){2}$/)[0]
"/world/bla.html"
Without regular expression:
> var s = '/foo/bar/baz/hello/world/bla.html';
> s.substr(s.lastIndexOf('/', s.lastIndexOf('/')-1))
"/world/bla.html"

I think this will work:
var str = "/foo/bar/baz/hello/world/bla.html";
alert( str.replace( /^.*?(\/[^/]*(?:\/[^/]*)?)$/, "$1") );
This will allow for there being possibly only one last part (like, "foo/bar").

You can use /(\/[^\/]*){2}$/ which selects a slash and some content twice followed by the end of the string.
See this regexplained.

Replace .split() with .match() using regex in javascript

I'm having difficulties with constructing some regular expressions using Javascript.
What I need:
I have a string like: Woman|{Man|Boy} or {Girl|Woman}|Man or Woman|Man etc.
I need to split this string by '|' separator, but I don't want it to be split inside curly brackets.
Examples of strings and desired results:
// Expample 1
string: 'Woman|{Man|Boy}'
result: [0] = 'Woman', [1] = '{Man|Boy}'
// Example 2
string '{Woman|Girl}|{Man|Boy}'
result: [0] = '{Woman|Girl}', [1] = '{Man|Boy}'
I can't change "|" symbol to another inside the brackets because the given strings are the result of a recursive function. For example, the original string could be
'Nature|Computers|{{Girls|Women}|{Boys|Men}}'

try this:
var reg=/\|(?![^{}]+})/g;
Example results:
var a = 'Woman|{Man|Boy}';
var b = '{Woman|Girl}|{Man|Boy}';
a.split(reg)
["Woman", "{Man|Boy}"]
b.split(reg)
["{Woman|Girl}", "{Man|Boy}"]
for your another question:
"Now I have another, but a bit similar problem. I need to parse all containers from the string. Syntax of the each container is {sometrash}. The problem is that container can contain another containers, but I need to parse only "the most relative" container. mystring.match(/\{+.+?\}+/gi); which I use doesn't work correctly. Could you correct this regex, please? "
you can use this regex:
var reg=/\{[^{}]+\}/g;
Example results:
var a = 'Nature|Computers|{{Girls|Women}|{Boys|Men}}';
a.match(reg)
["{Girls|Women}", "{Boys|Men}"]

You can use
.match(/[^|]+|\{[^}]*\}/g)
to match those. However, if you have a nesting of arbitrary depth then you'll need to use a parser, [javascript] regex won't be capable of doing that.

Test this:
([a-zA-Z0-9]*\|[a-zA-Z0-9]*)|{[a-zA-Z0-9]*\|[a-zA-Z0-9]*}

java script Regular Expressions patterns problem

My problem start with like-
var str='0|31|2|03|.....|4|2007'
str=str.replace(/[^|]\d*[^|]/,'5');
so the output becomes like:"0|5|2|03|....|4|2007" so it replaces 31->5
But this doesn't work for replacing other segments when i change code like this:
str=str.replace(/[^|]{2}\d*[^|]/,'6');
doesn't change 2->6.
What actually i am missing here.Any help?

I think a regular expression is a bad solution for that problem. I'd rather do something like this:
var str = '0|31|2|03|4|2007';
var segments = str.split("|");
segments[1] = "35";
segments[2] = "123";
Can't think of a good way to solve this with a regexp.

Here is a specific regex solution which replaces the number following the first | pipe symbol with the number 5:
var re = /^((?:\d+\|){1})\d+/;
return text.replace(re, '$15');
If you want to replace the digits following the third |, simply change the {1} portion of the regex to {3}
Here is a generalized function that will replace any given number slot (zero-based index), with a specified new number:
function replaceNthNumber(text, n, newnum) {
var re = new RegExp("^((?:\\d+\\|){"+ n +'})\\d+');
return text.replace(re, '$1'+ newnum);
}

Firstly, you don't have to escape | in the character set, because it doesn't have any special meaning in character sets.
Secondly, you don't put quantifiers in character sets.
And finally, to create a global matching expression, you have to use the g flag.

[^\|] means anything but a '|', so in your case it only matches a digit. So it will only match anything with 2 or more digits.
Second you should put the {2} outside of the []-brackets
I'm not sure what you want to achieve here.

Regex equivalent to str.substr(0, str.indexOf('foo'))

Given this string:
var str = 'A1=B2;C3,D0*E9+F6-';
I would like to retrieve the substring that goes from the beginning of the string up to 'D0*' (excluding), in this case:
'A1=B2;C3,'
I know how to achieve this using the combination of the substr and indexOf methods:
str.substr(0, str.indexOf('D0*'))
Live demo: http://jsfiddle.net/simevidas/XSu22/
However, this is obviously not the best solution since it contains a redundancy (the str name has to be written twice). This redundancy can be avoided by using the match method together with a regular expression that captures the substring:
str.match(/???/)[1]
Which regular expression literal do we have to pass into match to ensure that the correct substring is returned?
My guess is this: /(.*)D0\*/ (and that works), but my experience with regular expressions is rather limited, so I'm going to need a confirmation...

Try this:
/(.*?)D0\*/.exec(str)[1]
Or:
str.match(/(.*?)D0\*/)[1]
DEMO HERE
? directly following a quantifier makes the quantifier non-greedy (makes it match minimum instead of maximum of the interval defined).
Here's where that's from

/^(.+?)D0\*/
Try it here: http://rubular.com/r/TNTizJLSn9

/^.*(?=D0\*)/
more text to hit character limit...

You can do a number-group, like your example.
/^(.*?)foo/
It mean somethink like:
Store all in group, from start (the 0)
Stop, but don't store on found foo (the indexOf)
After that, you need match and get
'hello foo bar foo bar'.match(/^(.*?)foo/)[1]; // will return "hello "
It mean that will work on str variable and get the first (and unique) number-group existent. The [0] instead [1] mean that will get all matched code.
Bye :)

how to simplfy this code

What would be a good way to do this. I have a string with lots of "<" and > and I want to replace them with < and >. So i wrote this:
var str = </text><word34212>
var p = str.replace('\&lt\;','\<');
var m = p.replace('\&gt\;','\>');
but that's just doing the first instance of each - and subsequent instances of </> are not replaced. I considered first counting the instances of the < and then looping and replacing one instance of the code on every iteration...and then doing the same for the > but obviously this is quite long-winded.
Can anyone suggest a neater way to do this?

To replace multiple occurances you use a regular expression, so that you can specify the global (g) flag:
var m = str.replace(/</g,'<').replace(/>/g,'>');

Taken from: http://www.bradino.com/javascript/string-replace/
The JavaScript function for String
Replace replaces the first occurrence
in the string. The function is similar
to the php function str_replace and
takes two simple parameters. The first
parameter is the pattern to find and
the second parameter is the string to
replace the pattern with when found.
The javascript function does not
Replace All...
To ReplaceAll you have to do it a
little differently. To replace all
occurrences in the string, use the g
modifier like this:
str = str.replace(/find/g,”replace”)

You need to use the global modifier:
var p = str.replace(/\&lt\;/g,'\<');

You need to use de /g modifier in your regex and it'll work. Check this page for an example : http://www.w3schools.com/jsref/jsref_replace.asp

I thing a associative array [regex -> replacement] and one iteration would do it