Develop Reference

String.replace with special characters noting working

I have spent several hours trying to figure out what is going on here looking at stack overflow and elsewhere and I cannot figure out what is going on. I would really appreciate any help!!
I need to make document.write('< /div>'); go to -> < /div>
I've simplified it down to the simplest possible case with the html example below.
<script>
var str = "document.write('</div>');";
str = str.replace("/document.write/g","");
console.log(str); //</div>
</script>

Exclude the quotes and it works. It is being interpreted as a string literal because of the quotes, whereas a regular expression literal is expressed between plain /s.
Also, . needs to be escaped or it matches any other single character.
<script>
var str = "document.write('</div>');";
str = str.replace(/document\.write/g,"");
console.log(str); //</div>
</script>

String.prototype.replace() accepts either a string or a regex. If you are going with a string this should be:
var str = "document.write('</div>');";
str = str.replace("document.write","");
console.log(str);

Regex or lastIndexOf when removing last instance of a string

I couldn't apply answers to other similar questions (trying to replace the last occurrence of a string) because I am having trouble with the syntax.
I'm trying to replace the last occurrence of a string. The value of the string is stored in a variable that is passed to the .replace() method like this:
var str += some additive strings;
var del = a string that lives within str; // the value is dynamic
str = str.replace(del$, ''); // this doesn't work to remove the last occurrence of `del` in str
As I understand it the $ argument looks for the last occurrence of a string within a regex; but I can't figure out how to use it alongside a variable passed to .replace(). Any suggestions?

If you want to use the RegExp with a $, do it like this:
var str += 'some additive strings';
var re = new RegExp('a string that lives within str$');
str = str.replace(re, '');

str = str.substring(0, str.length - del.length);

You can use lastIndexOf() with slice()
Example:
var str ="HI this is cool isn't it? cool";
var del='cool';// put whatever here
var index = test.lastIndexOf(del);
var length=del.length;
if(index!=-1)
var removeStr=test.substr(index,length);
str.replace(removeStr,''); // HI this is cool isn't it?
Mate, this is just an answer. You'll need to use it according to your needs.
Updated Live demo:http://jsfiddle.net/n2Kgn/2

regex replace in javascript/jquery

I've never really used regex so this is probably a basic question, but I need to reformat a string in javascript/jquery and I think regex is the direction to go.
How can I convert this string:
\"1\",\"2\",\"\\",\"\4\"
into:
"1","2","","4"
These are both strings, so really they'd be contained in "" but I thought that may confuse things even more.
I've tried the following but it doesn't work:
var value = '\"1\",\"2\",\"\\",\"\4\"'.replace(/\"/, '"').replace(/"\//, '"');

Try:
var value = your_string.replace(/\\/g, "");
to remove all the "\"

It's a lot of escaping... Your string is:
var str = '\\"1\\",\\"2\\",\\"\\\\",\\"\\4\\"'
console.log(str.replace(/\\/g, '')) // "1","2","","4"
However, if you want only to replace \" with " use:
console.log(str.replace(/\\"/g, '"')) // "1","2","\","\4"

Simple Javascript string manipulation

I have a string that will look something like this:
I'm sorry the code "codehere" is not valid
I need to get the value inside the quotes inside the string. So essentially I need to get the codehere and store it in a variable.
After some researching it looks like I could loop through the string and use .charAt(i) to find the quotes and then pull the string out one character at a time in between the quotes.
However I feel there has to be a simpler solution for this out there. Any input would be appreciated. Thanks!

You could use indexOf and lastIndexOf to get the position of the quotes:
var openQuote = myString.indexOf('"'),
closeQuote = myString.lastIndexOf('"');
Then you can validate they are not the same position, and use substring to retrieve the code:
var code = myString.substring(openQuote, closeQuote + 1);

Regex:
var a = "I'm sorry the code \"codehere\" is not valid";
var m = a.match(/"[^"]*"/ig);
alert(m[0]);

Try this:
var str = "I'm sorry the code \"cod\"eh\"ere\" is not valid";
alert(str.replace(/^[^"]*"(.*)".*$/g, "$1"));

You could use Javascript's match function. It takes as parameter, a regular expression. Eg:
/\".*\"/

Use regular expressions! You can find a match using a simple regular expressions like /"(.+)"/ with the Javascript RegExp() object. Fore more info see w3schools.com.

Try this:
var msg = "I'm sorry the code \"codehere\" is not valid";
var matchedContent = msg.match(/\".*\"/ig);
//matchedContent is an array
alert(matchedContent[0]);

You should use a Regular Expression. This is a text pattern matcher that is built into the javascript language. Regular expressions look like this: /thing to match/flags* for example, /"(.*)"/, which matches everything between a set of quotes.
Beware, regular expressions are limited -- they can't match nested things, so if the value inside quotes contains quotes itself, you'll end up with a big ugly mess.
*: or new RegExp(...), but use the literal syntax; it's better.

You could always use the .split() string function:
var mystring = 'I\'m sorry the code "codehere" is not valid' ;
var tokens = [] ;
var strsplit = mystring.split('\"') ;
for(var i=0;i<strsplit.length;i++) {
if((i % 2)==0) continue; // Ignore strings outside the quotes
tokens.push(strsplit[i]) ; // Store strings inside quotes.
}
// Output:
// tokens[0] = 'codehere' ;

Splitting string in javascript

How can I split the following string?
var str = "test":"abc","test1":"hello,hi","test2":"hello,hi,there";
If I use str.split(",") then I won't be able to get strings which contain commas.
Whats the best way to split the above string?

I assume it's actually:
var str = '"test":"abc","test1":"hello,hi","test2":"hello,hi,there"';
because otherwise it wouldn't even be valid JavaScript.
If I had a string like this I would parse it as an incomplete JSON which it seems to be:
var obj = JSON.parse('{'+str+'}');
and then use is as a plain object:
alert(obj.test1); // says: hello,hi
See DEMO
Update 1: Looking at other answers I wonder whether it's only me who sees it as invalid JavaScript?
Update 2: Also, is it only me who sees it as a JSON without curly braces?

Though not clear with your input. Here is what I can suggest.
str.split('","');
and then append the double quotes to each string

str.split('","'); Difficult to say given the formatting
if Zed is right though you can do this (assuming the opening and closing {)
str = eval(str);
var test = str.test; // Returns abc
var test1 = str.test1; // returns hello,hi
//etc

That's a general problem in all languages: if the items you need contain the delimiter, it gets complicated.
The simplest way would be to make sure the delimiter is unique. If you can't do that, you will probably have to iterate over the quoted Strings manually, something like this:
var arr = [];
var result = text.match(/"([^"]*"/g);
for (i in result) {
arr.push(i);
}

Iterate once over the string and replace commas(,) following a (") and followed by a (") with a (%) or something not likely to find in your little strings. Then split by (%) or whatever you chose.