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JavaScript - Replace variable from string in all occurrences

OK, I know if I have say the character '-' and I want to remove it in all places in a string with JavaScript, I simply ...
someWord = someWord.replace(/-/g, '');
But, when applying this to an array of characters, it s not working ...
const badChars = ('\/:*?"<>|').split('');
let fileName = title.replace(/ /g, '-').toLocaleLowerCase();
for (let item = 0; item < badChars.length; item++) {
// below will not work with global '/ /g'
fileName = fileName.replace(/badChars[item]/g, '');
}
Any ideas?

/badChars[item]/g looks for badChars, literally, followed by an i, t, e, or m.
If you're trying to use the character badChars[item], you'll need to use the RegExp constructor, and you'll need to escape any regex-specific characters.
Escaping a regular expression has already been well-covered. So using that:
fileName = fileName.replace(new RegExp(RegExp.quote(badChars[item]), 'g'), '');
But, you really don't want that. You just want a character class:
let fileName = title.replace(/[\/:*?"<>|]/g, '-').toLocaleLowerCase();

Found it ....
fileName = fileName.replace(/[-\/\\^$*+?.()|[\]{}]/g, '');

Regular Expression to match compound words using only the first word

I am trying to create a regular expression in JS which will match the occurences of box and return the full compound word
Using the string:
the box which is contained within a box-wrap has a box-button
I would like to get:
[box, box-wrap, box-button]
Is this possible to match these words only using the string box?
This is what I have tried so far but it does not return the results I desire.
http://jsfiddle.net/w860xdme/
var str ='the box which is contained within a box-wrap has a box-button';
var regex = new RegExp('([\w-]*box[\w-]*)', 'g');
document.getElementById('output').innerHTML=str.match(regex);

Try this way:
([\w-]*box[\w-]*)
Regex live here.
Requested by comments, here is a working example in javascript:
function my_search(word, sentence) {
var pattern = new RegExp("([\\w-]*" + word + "[\\w-]*)", "gi");
sentence.replace(pattern, function(match) {
document.write(match + "<br>"); // here you can do what do you want
return match;
});
};
var phrase = "the box which is contained within a box-wrap " +
"has a box-button. it is inbox...";
my_search("box", phrase);
Hope it helps.

I'll just throw this out there:
(box[\w-]*)+

You can use this regex in JS:
var w = "box"
var re = new RegExp("\\b" + w + "\\S*");
RegEx Demo

This should work, note the 'W' is upper case.
http://www.w3schools.com/jsref/jsref_obj_regexp.asp
\Wbox\W

It looks like you're wanting to use the match with a regex. Match is a string method that will take a regex as an argument and return an array containing matches.
var str = "your string that contains all of the words you're looking for";
var regex = /you(\S)*(?=\s)/g;
var returnedArray = str.match(regex);
//console.log(returnedArray) returns ['you', 'you\'re']

RegEx to match words in comma delimited list

How can you match text that appears between delimiters, but not match the delimiters themselves?
Text
DoNotFindMe('DoNotFindMe')
DoNotFindMe(FindMe)
DoNotFindMe(FindMe,FindMe)
DoNotFindMe(FindMe,FindMe,FindMe)
Script
text = text.replace(/[\(,]([a-zA-Z]*)[,\)]/g, function(item) {
return "'" + item + "'";
});
Expected Result
DoNotFindMe('DoNotFindMe')
DoNotFindMe('FindMe')
DoNotFindMe('FindMe','FindMe')
DoNotFindMe('FindMe','FindMe','FindMe')
https://regex101.com/r/tB1nE2/1

Here's a pretty simple way to do it:
([a-zA-Z]+)(?=,|\))
This looks for any word that is succeeded by either a comma or a close-parenthesis.
var s = "DoNotFindMe('DoNotFindMe')\nDoNotFindMe(FindMe)\nDoNotFindMe(FindMe,FindMe)\nDoNotFindMe(FindMe,FindMe,FindMe)";
var r = s.replace(/([a-zA-Z]+)(?=,|\))/g, "'$1'" );
alert(r);
Used the same test code as the other two answers; thanks!

You can use:
var s = "DoNotFindMe('DoNotFindMe')\nDoNotFindMe(FindMe)\nDoNotFindMe(FindMe,FindMe)\nDoNotFindMe(FindMe,FindMe,FindMe)";
var r = s.replace(/(\([^)]+\))/g, function($0, $1) {
return $1.replace(/(\b[a-z]+(?=[,)]))/gi, "'$1'"); }, s);
DoNotFindMe('DoNotFindMe')
DoNotFindMe('FindMe')
DoNotFindMe('FindMe','FindMe')
DoNotFindMe('FindMe','FindMe','FindMe')

Here's a solution that avoids the function argument. It's a bit wonky, but works. Basically, you explicitly match the left delimiter and include it in the replacement string via backreference so it won't get dropped, but then you have to use a positive look-ahead assertion for the right delimiter, because otherwise the match pointer would be moved ahead of the right delimiter for the next match, and so it then wouldn't be able to match that delimiter as the left delimiter of the following delimited word:
var s = "DoNotFindMe('DoNotFindMe')\nDoNotFindMe(FindMe)\nDoNotFindMe(FindMe,FindMe)\nDoNotFindMe(FindMe,FindMe,FindMe)";
var r = s.replace(/([,(])([a-zA-Z]*)(?=[,)])/g, "$1'$2'" );
alert(r);
results in
DoNotFindMe('DoNotFindMe')
DoNotFindMe('FindMe')
DoNotFindMe('FindMe','FindMe')
DoNotFindMe('FindMe','FindMe','FindMe')
(Thanks anubhava, I stole your code template, cause it was perfect for my testing! I gave you an upvote for it.)

Replace a substring with javascript

Need to replace a substring in URL (technically just a string) with javascript.
The string like
http://blah-blah.com/search?par_one=test&par_two=anothertest&SearchableText=TO_REPLACE
or
http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest
means, the word to replace can be either at the most end of the URL or in the middle of it.
I am trying to cover these with the following:
var newWord = NEW_SEARCH_TERM;
var str = 'http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest';
var regex = /^\S+SearchableText=(.*)&?\S*$/;
str = str.replace(regex, newWord);
But no matter what I do I get str = NEW_SEARCH_TERM. Moreover the regular expression when I try it in RegExhibit, selects the word to replace and everything that follows it that is not what I want.
How can I write a universal expression to cover both cases and make the correct string be saved in the variable?

str.replace(/SearchableText=[^&]*/, 'SearchableText=' + newWord)

The \S+ and \S* in your regex match all non-whitespace characters.
You probably want to remove them and the anchors.

http://jsfiddle.net/mplungjan/ZGbsY/
ClyFish did it while I was fiddling
var url1="http://blah-blah.com/search?par_one=test&par_two=anothertest&SearchableText=TO_REPLACE";
var url2 ="http://blah-blah.com/search?par_one=test&SearchableText=TO_REPLACE&par_two=anothertest"
var newWord = "foo";
function replaceSearch(str,newWord) {
var regex = /SearchableText=[^&]*/;
return str.replace(regex, "SearchableText="+newWord);
}
document.write(replaceSearch(url1,newWord))
document.write('<hr>');
document.write(replaceSearch(url2,newWord))

Javascript regex - split string

Struggling with a regex requirement. I need to split a string into an array wherever it finds a forward slash. But not if the forward slash is preceded by an escape.
Eg, if I have this string:
hello/world
I would like it to be split into an array like so:
arrayName[0] = hello
arrayName[1] = world
And if I have this string:
hello/wo\/rld
I would like it to be split into an array like so:
arrayName[0] = hello
arrayName[1] = wo/rld
Any ideas?

I wouldn't use split() for this job. It's much easier to match the path components themselves, rather than the delimiters. For example:
var subject = 'hello/wo\\/rld';
var regex = /(?:[^\/\\]+|\\.)+/g;
var matched = null;
while (matched = regex.exec(subject)) {
print(matched[0]);
}
output:
hello
wo\/rld
test it at ideone.com

The following is a little long-winded but will work, and avoids the problem with IE's broken split implementation by not using a regular expression.
function splitPath(str) {
var rawParts = str.split("/"), parts = [];
for (var i = 0, len = rawParts.length, part; i < len; ++i) {
part = "";
while (rawParts[i].slice(-1) == "\\") {
part += rawParts[i++].slice(0, -1) + "/";
}
parts.push(part + rawParts[i]);
}
return parts;
}
var str = "hello/world\\/foo/bar";
alert( splitPath(str).join(",") );

Here's a way adapted from the techniques in this blog post:
var str = "Testing/one\\/two\\/three";
var result = str.replace(/(\\)?\//g, function($0, $1){
return $1 ? '/' : '[****]';
}).split('[****]');
Live example
Given:
Testing/one\/two\/three
The result is:
[0]: Testing
[1]: one/two/three
That first uses the simple "fake" lookbehind to replace / with [****] and to replace \/ with /, then splits on the [****] value. (Obviously, replace [****] with anything that won't be in the string.)

/*
If you are getting your string from an ajax response or a data base query,
that is, the string has not been interpreted by javascript,
you can match character sequences that either have no slash or have escaped slashes.
If you are defining the string in a script, escape the escapes and strip them after the match.
*/
var s='hello/wor\\/ld';
s=s.match(/(([^\/]*(\\\/)+)([^\/]*)+|([^\/]+))/g) || [s];
alert(s.join('\n'))
s.join('\n').replace(/\\/g,'')
/* returned value: (String)
hello
wor/ld
*/

Here's an example at rubular.com

For short code, you can use reverse to simulate negative lookbehind
function reverse(s){
return s.split('').reverse().join('');
}
var parts = reverse(myString).split(/[/](?!\\(?:\\\\)*(?:[^\\]|$))/g).reverse();
for (var i = parts.length; --i >= 0;) { parts[i] = reverse(parts[i]); }
but to be efficient, it's probably better to split on /[/]/ and then walk the array and rejoin elements that have an escape at the end.

Something like this may take care of it for you.
var str = "/hello/wo\\/rld/";
var split = str.replace(/^\/|\\?\/|\/$/g, function(match) {
if (match.indexOf('\\') == -1) {
return '\x00';
}
return match;
}).split('\x00');
alert(split);