Develop Reference

Javascript regex to add to every character of a string a backslash

So as the title says I'd like to add to every character of a string a backslash, whether the string has special characters or not. The string should not be considered 'safe'
eg:
let str = 'dj%^3&something';
str = str.replace(x, y);
// str = '\d\j\%\^\3\&\s\o\m\e\t\h\i\n\g'

You could capture every character in the string with (.) and use \\$1 as replacement, I'm not an expert but basically \\ will render to \ and $1 will render to whatever (.) captures.
HIH
EDIT
please refer to Wiktor Stribiżew's comment for an alternative which will require less coding. Changes as follows:
str = str.replace(/(.)/g, '\\$1'); for str = str.replace(/./g, '\\$&');
Also, for future reference I strongly advice you to visit regexr.com when it comes to regular expressions, it's helped ME a lot
let str = 'dj%^3&something';
str = str.replace(/(.)/g, '\\$1');
console.log(str);

If you just want to display a string safely, you should just do:
let str = 'dj%^3&something';
let node = document.createTextNode(str);
let dest = document.querySelector('.whatever');
dest.appendChild(node);
And then you are guaranteed that it will be treated as text, and won't be able to execute a script or anything.
For example: https://jsfiddle.net/s6udj03L/1/

You can split the string to an array, add a \ to each element to the array, then joint the array back to the string that you wanted.
var str = 'dj%^3&something';
var split = str.split(""); // split string into array
for (var i = 0; i < split.length; i++) {
split[i] = '\\' + split[i]; // add backslash to each element in array
}
var joint = split.join('') // joint array to string
console.log(joint);

If you don't care about creating a new string and don't really have to use a regex, why not just iterate over the existing one and place a \ before each char. Notice to you have to put \\ to escape the first \.
To consider it safe, you have to encode it somehow. You could replace typical 'non-safe' characters like in the encode() function below. Notice how & get's replaced by &
let str = 'dj%^3&something';
let out = "";
for(var i = 0; i < str.length; i++) {
out += ("\\" + str[i]);
}
console.log(out);
console.log(encode(out));
function encode(string) {
return String(string).replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>').replace(/"/g, '"');
}

Splitting string to array while ignoring content between apostrophes

I need something that takes a string, and divides it into an array.
I want to split it after every space, so that this -
"Hello everybody!" turns into ---> ["Hello", "Everybody!"]
However, I want it to ignore spaces inbetween apostrophes. So for examples -
"How 'are you' today?" turns into ---> ["How", "'are you'", "today?"]
Now I wrote the following code (which works), but something tells me that what I did is pretty much horrible and that it can be done with probably 50% less code.
I'm also pretty new to JS so I guess I still don't adhere to all the idioms of the language.
function getFixedArray(text) {
var textArray = text.split(' '); //Create an array from the string, splitting by spaces.
var finalArray = [];
var bFoundLeadingApostrophe = false;
var bFoundTrailingApostrophe = false;
var leadingRegExp = /^'/;
var trailingRegExp = /'$/;
var concatenatedString = "";
for (var i = 0; i < textArray.length; i++) {
var text = textArray[i];
//Found a leading apostrophe
if(leadingRegExp.test(text) && !bFoundLeadingApostrophe && !trailingRegExp.test(text)) {
concatenatedString =concatenatedString + text;
bFoundLeadingApostrophe = true;
}
//Found the trailing apostrophe
else if(trailingRegExp.test(text ) && !bFoundTrailingApostrophe) {
concatenatedString = concatenatedString + ' ' + text;
finalArray.push(concatenatedString);
concatenatedString = "";
bFoundLeadingApostrophe = false;
bFoundTrailingApostrophe = false;
}
//Found no trailing apostrophe even though the leading flag indicates true, so we want this string.
else if (bFoundLeadingApostrophe && !bFoundTrailingApostrophe) {
concatenatedString = concatenatedString + ' ' + text;
}
//Regular text
else {
finalArray.push(text);
}
}
return finalArray;
}
I would deeply appreciate it if somebody could go through this and teach me how this should be rewritten, in a more correct & efficient way (and perhaps a more "JS" way).
Thanks!
Edit -
Well I just found a few problems, some of which I fixed, and some I'm not sure how to handle without making this code too complex (for example the string "hello 'every body'!" doesn't split properly....)

You could try matching instead of splitting:
string.match(/(?:['"].+?['"])|\S+/g)
The above regex will match anything in between quotes (including the quotes), or anything that's not a space otherwise.
If you want to also match characters after the quotes, like ? and ! you can try:
/(?:['"].+?['"]\W?)|\S+/g
For "hello 'every body'!" it will give you this array:
["hello", "'every body'!"]
Note that \W matches space as well, if you want to match punctuation you could be explicit by using a character class in place of \W
[,.?!]
Or simply trim the strings after matching:
string.match(regex).map(function(x){return x.trim()})

I need to escape double quotes in javascript

In the example below I run str through .replace and populate the div with id of wtf with the output. The problem is I have to manually escape the double quotes for str.replace to work.
Is there a way to automatically escape the double quotes?
<body>
<div id="wtf"></div>
<script>
var str = ("this string has "double quotes" as well as 'single quotes'..");
var well = str.replace(/\s\d{2}\s(\d{2}\s)?/g,' ');
wtf.innerHTML = well;
</script>
</body>

You must escape the double quotes manually. There's no way to do automatically because the str produce the following error then javascript wouldn't execute further ahead lines of code:

Use the backslash ( \ ) to escape your double quotes.
It should look like this :
var str = ("this string has \"double quotes\" as well as 'single quotes'..");
There's no automatic way to do this.

If you want to replace the quotes, it is best to replace them with their HTML entity. Using a method like this, you can accomplish it.
var tokens = [
['"', '"'],
["'", ''']
];
var clean = [];
for(var i = 0; i < MY_STRING.length; i++) {
var s = MY_STRING[i];
for(var a = 0; a < tokens.length; a++)
if(tokens[a][0] == s) {
s = tokens[a][1];
break;
}
clean.push(s);
}
var cleanString = clean.join("");

Remove a letter(:) from a string

I have strings like Name:, Call:, Phone:....and so on in my table. I am learning jQuery and was able to access the text. My tutorial has used trim() to remove any whitespaces. But I want o remove ":" from the end of each string (and yes, it always lies in the end after calling trim() method). So how to achieve it.
Its my code:
<script type="text/javascript">
$(function ()
{
$(':input[type=text], textarea').each
(
function ()
{
var newText = 'Please enter your ' +
$(this).parent().prev().text().toLowerCase().trim();
$(this).attr('value', newText);
}).one('focus', function ()
{
this.value = '', this.className = ''
}).addClass('Watermark').css('width', '300px');
});
</script>
trim(":") did not help...

You can replace all : characters:
var str = '::a:sd:';
str = str.replace(/:/g,''); // str = 'asd';
Or use a handy rtrim() function:
String.prototype.rtrim = function(character) {
var re = new RegExp(character + '*$', 'g');
return this.replace(re, '');
};
var str = '::a:sd:';
str = str.rtrim(':'); // str = '::a:sd';

In this case just use the plain old JavaScript replace or substr methods.
You can also use a regular expression that looks for colon as the last character (the character preceding the regexp end-of-string anchor "$").
"hi:".replace(/:$/, "")
hi
"hi".replace(/:$/, "")
hi
"h:i".replace(/:$/, "")
h:i
This is a simplified, inline version of the rtrim function in Blender's answer.
EDIT: Here is a test fiddle for Blender's corrected rtrim function. Note that his RegExp will delete multiple occurrences of the specified character if the string ends with multiple instances of it consecutively (example bolded below).
http://jsfiddle.net/fGrPb/5/
input = '::a:sd:' output = '::a:sd'; input = 'hi:' output = 'hi'; input = 'hi:::' output = 'hi'; input = 'hi' output = 'hi'; input = 'h:i' output = 'h:i'

To chop the last character of a string use string.slice(0,-1)

You can use a regular expression to remove the colon (:).
Replace one instance:
var with_colon = 'Stuff:';
var regex = /([^:]*):/;
var without_colon = regex.exec(with_colon)[1];
alert(without_colon);
Result: Stuff
Replace all instances:
var with_colon = 'Stuff: Things:';
var without_colon = with_colon.replace(/([^:]*):/g,'$1');
alert(without_colon);
Result: Stuff Things

var myStr = "something:";
myStr = myStr.slice(0, -1);

var a="name:";
var b=a.split(":");
alert(b[0]);

one way is to use lastIndexOf
var str='Name:, Call:, Phone:';
var index=str.lastIndexOf(":");
alert(index);
var s=str.substring(0,index);
alert(s);
DEMO

This checks if the last character is a colon. If it is, the last character is removed.
if (str[str.length - 1] === ":") {
str = str.slice(0, -1);
}
If there can be multiple trailing colons, you can replace if with while, like this:
while (str[str.length - 1] === ":") {
str = str.slice(0, -1);
}
You could even make a generic trim function that accepts a string and a character and trims trailing instances of that character:
var trim = function(str, chr) {
while (str[str.length - 1] === ":") {
str = str.slice(0, -1);
}
return str;
}

function trim(str) {
str = str.replace(/^:*/,"");
return str.replace(/:*$/,"");
}

str = str.substring(0,str.lastIndexOf(":"));
Note that this removes everything from the last : to the end of the string (for example, any whitespace after the :).

How to globally replace a forward slash in a JavaScript string?

How to globally replace a forward slash in a JavaScript string?

The following would do but only will replace one occurence:
"string".replace('/', 'ForwardSlash');
For a global replacement, or if you prefer regular expressions, you just have to escape the slash:
"string".replace(/\//g, 'ForwardSlash');

Use a regex literal with the g modifier, and escape the forward slash with a backslash so it doesn't clash with the delimiters.
var str = 'some // slashes', replacement = '';
var replaced = str.replace(/\//g, replacement);

You need to wrap the forward slash to avoid cross browser issues or //commenting out.
str = 'this/that and/if';
var newstr = str.replace(/[/]/g, 'ForwardSlash');

Without using regex (though I would only do this if the search string is user input):
var str = 'Hello/ world/ this has two slashes!';
alert(str.split('/').join(',')); // alerts 'Hello, world, this has two slashes!'

Is this what you want?
'string with / in it'.replace(/\//g, '\\');

This has worked for me in turning "//" into just "/".
str.replace(/\/\//g, '/');

Hi a small correction in the above script..
above script skipping the first character when displaying the output.
function stripSlashes(x)
{
var y = "";
for(i = 0; i < x.length; i++)
{
if(x.charAt(i) == "/")
{
y += "";
}
else
{
y+= x.charAt(i);
}
}
return y;
}

This is Christopher Lincolns idea but with correct code:
function replace(str,find,replace){
if (find){
str = str.toString();
var aStr = str.split(find);
for(var i = 0; i < aStr.length; i++) {
if (i > 0){
str = str + replace + aStr[i];
}else{
str = aStr[i];
}
}
}
return str;
}
Example Usage:
var somevariable = replace('//\\\/\/sdfas/\/\/\\\////','\/sdf','replacethis\');
Javascript global string replacement is unecessarily complicated. This function solves that problem. There is probably a small performance impact, but I'm sure its negligable.
Heres an alternative function, looks much cleaner, but is on average about 25 to 20 percent slower than the above function:
function replace(str,find,replace){
if (find){
str = str.toString().split(find).join(replace);
}
return str;
}

var str = '/questions'; // input: "/questions"
while(str.indexOf('/') != -1){
str = str.replace('/', 'http://stackoverflow.com/');
}
alert(str); // output: "http://stackoverflow.com/questions"
The proposed regex /\//g did not work for me; the rest of the line (//g, replacement);) was commented out.

You can create a RegExp object to make it a bit more readable
str.replace(new RegExp('/'), 'foobar');
If you want to replace all of them add the "g" flag
str.replace(new RegExp('/', 'g'), 'foobar');