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, '"');
}
I have made this very simplified version of a translation tool similar to Google Translate. The idea is to build this simple tool for a minority language in sweden called "jamska". The app is built up with a function that takes the string from a textarea with the ID #svenska and replaces words in the string using RegExp.
I've made an array called arr that's used in a for loop of the function as a dictionary. Each array item looks like this: var arr = [["eldröd", "eillrau"], ["oväder", "over"] ...]. The first word in each array item is in swedish, and the second word is in jamska. If the RegExp finds a matching word in the loop it replaces that word using this code:
function translate() {
var str = $("#svenska").val();
var newStr = "";
for (var i = 0; i < arr.length; i++) {
var replace = arr[i][0];
var replaceWith = arr[i][1];
var re = new RegExp('(^|[^a-z0-9åäö])' + replace + '([^a-z0-9åäö]|$)', 'ig');
str = str.replace(re, "$1" + replaceWith + '$2');
}
$("#jamska").val(str);
}
The translate() is then called in an event handler for when the #svenska textarea gets a keyup, like this: $("#svenska").keyup(function() { translate(); });
The translated string is then assigned as the value of another textarea with the ID #jamska. So far, so good.
I have a problem though: if the translated word in jamska also is a word in swedish, the function translates that word too. This problem is occurring because I'm assigning the variable str to the translated version of the same variable, using: str = str.replace(re, "$1" + replaceWith + '$2');. The function is using the same variable over and over again to perform the translation.
Example:
The swedish word "brydd" is "fel" in jamska. "Fel" is also a word in swedish, so the word that I get after the translation is "felht", since the swedish word "fel" is "felht" in jamska.
Does anyone have any idea for how to work around this problem?
Instead of looking for each Jamska word in the input and replacing them with the respective translation, I would recommend to find any word ([a-z0-9åäö]+) in your text and replace this word either with its translation if one is found in the dictionary or with itself otherwise:
//var arr = [["eldröd", "eillrau"], ["oväder", "over"] ...]
// I'd better use dictionary instead of array to define your dictionary
var dict = {
eldröd: "oväder",
eillrau: "over"
// ...
};
var str = "eldröd test eillrau eillrau oväder over";
var translated = str.replace(/[a-z0-9åäö]+/ig, function(m) {
var word = m.toLowerCase();
var trans = dict[word];
return trans === undefined ? word : trans;
});
console.log(translated);
Update:
If dictionary keys may be represented by phrases (i.e. technically appear as strings with spaces), the regex should be extended to include all these phrases explicitly. So the final regex would look like
(?:phrase 1|phrase 2|etc...)(?![a-z0-9åäö])|[a-z0-9åäö]+
It will try to match one of the phrases explicitly first and only then single words. The (?![a-z0-9åäö]) lookbehind helps to filter out phrases immediately followed by letters (e.g. varken bättre eller sämreåäö).
Phrases immediately preceded by letters are implicitly filtered out by the fact that a match is either the fist one (and therefore is not preceded by any letter) or it's not the first and therefore the previous one is separated from the current by some spaces.
//var arr = [["eldröd", "eillrau"], ["oväder", "over"] ...]
// I'd better use dictionary instead of array to define your dictionary
var dict = {
eldröd: "oväder",
eillrau: "over",
bättre: "better",
"varken bättre eller sämre": "vär å int viller",
"test test": "double test"
// ...
};
var str = "eldröd test eillrau eillrau oväder over test test ";
str += "varken bättre eller sämre ";
str += "don't trans: varken bättre eller sämreåäö";
str += "don't trans again: åäövarken bättre eller sämre";
var phrases = Object.keys(dict)
.filter(function(k) { return /\s/.test(k); })
.sort(function(a, b) { return b.length - a.length; })
.join('|');
var re = new RegExp('(?:' + phrases + ')(?![a-z0-9åäö])|[a-z0-9åäö]+', 'ig');
var translated = str.replace(re, function(m) {
var word = m.toLowerCase();
var trans = dict[word];
return trans === undefined ? word : trans;
});
console.log(translated);
On my website I have a commentary field, where people can write whatever they want. To prevent spam and unserious comments, I'm using an angular filter in this way:
<span>{{comment | mouthWash}}</span>
The angular filter fetches an array containing banned words and scans through the input string and replaces all the occurences of the fetched words. The code for the filter is as below:
app.filter('mouthWash', function($http) {
var badWords;
$http.get('js/objects/bad-words.json').success(function (data) {
badWords = data;
});
return function(input) {
angular.forEach(badWords, function(word){
var regEx = new RegExp(word);
input = input.replace(regEx, "mooh");
});
return input;
};
});
bad-words.json is something like this:
["fuck", "ass", "shit", etc...]
So as an example <span>{{ "fuck this" | mouthWash}}</span> is outputted as <span>mooh this</span>
This is working perfectly, except that I want it to ignore whitespaces, to make it more bullet proof. I do not have much experience with regex, so if anyone had a simple soloution to this, I would be really grateful.
just change new RegExp(word, "ig"); to new RegExp("ig");
working example:
var words = ['pig', 'dog', '', ' ', 'cow'];
words.forEach(function(word) {
var regEx = new RegExp("ig");
word = word.replace(regEx, "mooh");
console.log(word);
});
Output:
"pmooh"
"dog"
""
" "
"cow"
This is the code I ended up with:
app.filter('mouthWash', function($http) {
var badWords;
$http.get('js/objects/bad-words.json').success(function (data) {
badWords = data;
});
return function(input) {
angular.forEach(badWords, function(word){
var str = word.substring(0,1)+"\\s*";
for (var i = 1; i < word.length - 1; i++) str = str + word.substring(i,i+1)+"\\s*";
str = str + word.substring(word.length - 1,word.length);
var regEx = new RegExp(str, "gi");
input = input.replace(regEx, "mooh");
});
return input;
};
});
I created a for loop that would loop through every character of the banned word, adding the character together with \s* (so that spaces was ignored) to a string.
for (var i = 1; i < word.length - 1; i++) str = str + word.substring(i,i+1)+"\\s*";
Then created a regExp from the string, by using the regExp constructor with the string as first parameter and "gi" as second, to make the regExp global and case insensitive.
var regEx = new RegExp(str, "gi");
Then that regex was used to search through input string and replace all matches with "mooh".
How do I reverse the words in this string including the punctuation?
String.prototype.reverse = function () {
return this.split('').reverse().join('');
}
var str = "This is fun, hopefully.";
str.reverse();
Currently I am getting this:
".yllufepoh ,nuf si sihT"
When I want to return this:
"sihT si nuf, yllufepoh."
You could reverse each word instead of the whole string, but you have to keep spaces, periods etc seperate, so a word boundary is needed
String.prototype.reverse = function () {
return this.split(/\b/g).map(function(word) {
return word.split('').reverse().join('');
}).join('');
}
var str = "This is fun, hopefully.";
document.body.innerHTML = str.reverse();
Note that this moves the comma one space as it gets the comma and the space in one boundary and swaps them. If the comma needs to stay in the same spot, split on spaces as well, and change the regex to /(\b|\s)/g
Simply reversing the string wont give the solution.
Get each word.
Reverse It
Again rejoin
var str = "This is fun, hopefully.";
alert(str.split("").reverse().join("").split(" ").reverse().join(" "));
You can imagine that you receive a stream of letters and you have to construct words based on some separators (like: spaces, commas, dashes .etc).
While reading each character you keep constructing the word in reverse.
When you hit any separator you finished the word.
Now you just add it to the result and append the separator (this way the separators will not be put at the beginning of the word, but at the end).
Here is an example:
const inputString = "HELLO, Welcome to Google's meeting. My name is Jean-Piere... Bye";
console.log('Normal words: ', inputString);
const result = reverseWords(inputString);
console.log('Words reversed: ', result);
function reverseWords(str='', separators=' ,.-') {
let result = '';
let word = '';
for (const char of str) {
if (separators.includes(char)) {
result += word + char;
word = '';
} else {
word = char + word;
}
}
// Adds last remaining word, if there is no separator at the end.
result += word;
return result;
}
const str = "This is fun, hopefully.";
function reverseWords(str){
const tempArr= str.split(" ")
let reversedTempArr=''
for(let i=0; i<tempArr.length;i++){
let tempStr=''
for(let j=tempArr[i].length-1;j>=0;j--){
tempStr += tempArr[i][j]
}
reversedTempArr += tempStr+ " "
}
return reversedTempArr
}
console.log(reverseWords(str))
You can reverse each word in a string in squence by splitting that word in to an array of words and then reversing each word and storing it in a new array and then joining that array as shown below.
//1) Reverse words
function reverseWords(str) {
// Go for it
let reversed;
let newArray=[];
reversed = str.split(" ");
for(var i = 0;i<reversed.length; i++)
{
newArray.push(reversed[i].split("").reverse().join(""));
}
return newArray.join(" ");
}
let reversedString = reverseWords("This is fun, hopefully.");
console.log("This is the reversed string : ",reversedString);
I want to use str_replace or its similar alternative to replace some text in JavaScript.
var text = "this is some sample text that i want to replace";
var new_text = replace_in_javascript("want", "dont want", text);
document.write(new_text);
should give
this is some sample text that i dont want to replace
If you are going to regex, what are the performance implications in
comparison to the built in replacement methods.
You would use the replace method:
text = text.replace('old', 'new');
The first argument is what you're looking for, obviously. It can also accept regular expressions.
Just remember that it does not change the original string. It only returns the new value.
More simply:
city_name=city_name.replace(/ /gi,'_');
Replaces all spaces with '_'!
All these methods don't modify original value, returns new strings.
var city_name = 'Some text with spaces';
Replaces 1st space with _
city_name.replace(' ', '_'); // Returns: "Some_text with spaces" (replaced only 1st match)
Replaces all spaces with _ using regex. If you need to use regex, then i recommend testing it with https://regex101.com/
city_name.replace(/ /gi,'_'); // Returns: Some_text_with_spaces
Replaces all spaces with _ without regex. Functional way.
city_name.split(' ').join('_'); // Returns: Some_text_with_spaces
You should write something like that :
var text = "this is some sample text that i want to replace";
var new_text = text.replace("want", "dont want");
document.write(new_text);
The code that others are giving you only replace one occurrence, while using regular expressions replaces them all (like #sorgit said). To replace all the "want" with "not want", us this code:
var text = "this is some sample text that i want to replace";
var new_text = text.replace(/want/g, "dont want");
document.write(new_text);
The variable "new_text" will result in being "this is some sample text that i dont want to replace".
To get a quick guide to regular expressions, go here:
http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/
To learn more about str.replace(), go here:
https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/String/replace
Good luck!
that function replaces only one occurrence.. if you need to replace
multiple occurrences you should try this function:
http://phpjs.org/functions/str_replace:527
Not necessarily.
see the Hans Kesting answer:
city_name = city_name.replace(/ /gi,'_');
Using regex for string replacement is significantly slower than using a string replace.
As demonstrated on JSPerf, you can have different levels of efficiency for creating a regex, but all of them are significantly slower than a simple string replace. The regex is slower because:
Fixed-string matches don't have backtracking, compilation steps, ranges, character classes, or a host of other features that slow down the regular expression engine. There are certainly ways to optimize regex matches, but I think it's unlikely to beat indexing into a string in the common case.
For a simple test run on the JS perf page, I've documented some of the results:
<script>
// Setup
var startString = "xxxxxxxxxabcxxxxxxabcxx";
var endStringRegEx = undefined;
var endStringString = undefined;
var endStringRegExNewStr = undefined;
var endStringRegExNew = undefined;
var endStringStoredRegEx = undefined;
var re = new RegExp("abc", "g");
</script>
<script>
// Tests
endStringRegEx = startString.replace(/abc/g, "def") // Regex
endStringString = startString.replace("abc", "def", "g") // String
endStringRegExNewStr = startString.replace(new RegExp("abc", "g"), "def"); // New Regex String
endStringRegExNew = startString.replace(new RegExp(/abc/g), "def"); // New Regexp
endStringStoredRegEx = startString.replace(re, "def") // saved regex
</script>
The results for Chrome 68 are as follows:
String replace: 9,936,093 operations/sec
Saved regex: 5,725,506 operations/sec
Regex: 5,529,504 operations/sec
New Regex String: 3,571,180 operations/sec
New Regex: 3,224,919 operations/sec
From the sake of completeness of this answer (borrowing from the comments), it's worth mentioning that .replace only replaces the first instance of the matched character. Its only possible to replace all instances with //g. The performance trade off and code elegance could be argued to be worse if replacing multiple instances name.replace(' ', '_').replace(' ', '_').replace(' ', '_'); or worse while (name.includes(' ')) { name = name.replace(' ', '_') }
var new_text = text.replace("want", "dont want");
hm.. Did you check replace() ?
Your code will look like this
var text = "this is some sample text that i want to replace";
var new_text = text.replace("want", "dont want");
document.write(new_text);
JavaScript has replace() method of String object for replacing substrings. This method can have two arguments. The first argument can be a string or a regular expression pattern (regExp object) and the second argument can be a string or a function. An example of replace() method having both string arguments is shown below.
var text = 'one, two, three, one, five, one';
var new_text = text.replace('one', 'ten');
console.log(new_text) //ten, two, three, one, five, one
Note that if the first argument is the string, only the first occurrence of the substring is replaced as in the example above. To replace all occurrences of the substring you need to provide a regular expression with a g (global) flag. If you do not provide the global flag, only the first occurrence of the substring will be replaced even if you provide the regular expression as the first argument. So let's replace all occurrences of one in the above example.
var text = 'one, two, three, one, five, one';
var new_text = text.replace(/one/g, 'ten');
console.log(new_text) //ten, two, three, ten, five, ten
Note that you do not wrap the regular expression pattern in quotes which will make it a string not a regExp object. To do a case insensitive replacement you need to provide additional flag i which makes the pattern case-insensitive. In that case the above regular expression will be /one/gi. Notice the i flag added here.
If the second argument has a function and if there is a match the function is passed with three arguments. The arguments the function gets are the match, position of the match and the original text. You need to return what that match should be replaced with. For example,
var text = 'one, two, three, one, five, one';
var new_text = text.replace(/one/g, function(match, pos, text){
return 'ten';
});
console.log(new_text) //ten, two, three, ten, five, ten
You can have more control over the replacement text using a function as the second argument.
In JavaScript, you call the replace method on the String object, e.g. "this is some sample text that i want to replace".replace("want", "dont want"), which will return the replaced string.
var text = "this is some sample text that i want to replace";
var new_text = text.replace("want", "dont want"); // new_text now stores the replaced string, leaving the original untouched
You can use
text.replace('old', 'new')
And to change multiple values in one string at once, for example to change # to string v and _ to string w:
text.replace(/#|_/g,function(match) {return (match=="#")? v: w;});
There are already multiple answers using str.replace() (which is fair enough for this question) and regex but you can use combination of str.split() and join() together which is faster than str.replace() and regex.
Below is working example:
var text = "this is some sample text that i want to replace";
console.log(text.split("want").join("dont want"));
If you really want a equivalent to PHP's str_replace you can use Locutus. PHP's version of str_replace support more option then what the JavaScript String.prototype.replace supports.
For example tags:
//PHP
$bodytag = str_replace("%body%", "black", "<body text='%body%'>");
//JS with Locutus
var $bodytag = str_replace(['{body}', 'black', '<body text='{body}'>')
or array's
//PHP
$vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U");
$onlyconsonants = str_replace($vowels, "", "Hello World of PHP");
//JS with Locutus
var $vowels = ["a", "e", "i", "o", "u", "A", "E", "I", "O", "U"];
var $onlyconsonants = str_replace($vowels, "", "Hello World of PHP");
Also this doesn't use regex instead it uses for loops. If you not want to use regex but want simple string replace you can use something like this ( based on Locutus )
function str_replace (search, replace, subject) {
var i = 0
var j = 0
var temp = ''
var repl = ''
var sl = 0
var fl = 0
var f = [].concat(search)
var r = [].concat(replace)
var s = subject
s = [].concat(s)
for (i = 0, sl = s.length; i < sl; i++) {
if (s[i] === '') {
continue
}
for (j = 0, fl = f.length; j < fl; j++) {
temp = s[i] + ''
repl = r[0]
s[i] = (temp).split(f[j]).join(repl)
if (typeof countObj !== 'undefined') {
countObj.value += ((temp.split(f[j])).length - 1)
}
}
}
return s[0]
}
var text = "this is some sample text that i want to replace";
var new_text = str_replace ("want", "dont want", text)
document.write(new_text)
for more info see the source code https://github.com/kvz/locutus/blob/master/src/php/strings/str_replace.js
You have the following options:
Replace the first occurrence
var text = "this is some sample text that i want to replace and this i WANT to replace as well.";
var new_text = text.replace('want', 'dont want');
// new_text is "this is some sample text that i dont want to replace and this i WANT to replace as well"
console.log(new_text)
Replace all occurrences - case sensitive
var text = "this is some sample text that i want to replace and this i WANT to replace as well.";
var new_text = text.replace(/want/g, 'dont want');
// new_text is "this is some sample text that i dont want to replace and this i WANT to replace as well
console.log(new_text)
Replace all occurrences - case insensitive
var text = "this is some sample text that i want to replace and this i WANT to replace as well.";
var new_text = text.replace(/want/gi, 'dont want');
// new_text is "this is some sample text that i dont want to replace and this i dont want to replace as well
console.log(new_text)
More info -> here
In Javascript, replace function available to replace sub-string from given string with new one.
Use:
var text = "this is some sample text that i want to replace";
var new_text = text.replace("want", "dont want");
console.log(new_text);
You can even use regular expression with this function. For example, if want to replace all occurrences of , with ..
var text = "123,123,123";
var new_text = text.replace(/,/g, ".");
console.log(new_text);
Here g modifier used to match globally all available matches.
Method to replace substring in a sentence using React:
const replace_in_javascript = (oldSubStr, newSubStr, sentence) => {
let newStr = "";
let i = 0;
sentence.split(" ").forEach(obj => {
if (obj.toUpperCase() === oldSubStr.toUpperCase()) {
newStr = i === 0 ? newSubStr : newStr + " " + newSubStr;
i = i + 1;
} else {
newStr = i === 0 ? obj : newStr + " " + obj;
i = i + 1;
}
});
return newStr;
};
RunMethodHere
If you don't want to use regex then you can use this function which will replace all in a string
Source Code:
function ReplaceAll(mystring, search_word, replace_with)
{
while (mystring.includes(search_word))
{
mystring = mystring.replace(search_word, replace_with);
}
return mystring;
}
How to use:
var mystring = ReplaceAll("Test Test", "Test", "Hello");
Use JS String.prototype.replace first argument should be Regex pattern or String and Second argument should be a String or function.
str.replace(regexp|substr, newSubStr|function);
Ex:
var str = 'this is some sample text that i want to replace';
var newstr = str.replace(/want/i, "dont't want");
document.write(newstr); // this is some sample text that i don't want to replace
ES2021 / ES12
String.prototype.replaceAll()
is trying to bring the full replacement option even when the input pattern is a string.
const str = "Backbencher sits at the Back";
const newStr = str.replaceAll("Back", "Front");
console.log(newStr); // "Frontbencher sits at the Front"
1- String.prototype.replace()
We can do a full **replacement** only if we supply the pattern as a regular expression.
const str = "Backbencher sits at the Back";
const newStr = str.replace(/Back/g, "Front");
console.log(newStr); // "Frontbencher sits at the Front"
If the input pattern is a string, replace() method only replaces the first occurrence.
const str = "Backbencher sits at the Back";
const newStr = str.replace("Back", "Front");
console.log(newStr); // "Frontbencher sits at the Back"
2- You can use split and join
const str = "Backbencher sits at the Back";
const newStr = str.split("Back").join("Front");
console.log(newStr); // "Frontbencher sits at the Front"
function str_replace($old, $new, $text)
{
return ($text+"").split($old).join($new);
}
You do not need additional libraries.
In ECMAScript 2021, you can use replaceAll can be used.
const str = "string1 string1 string1"
const newStr = str.replaceAll("string1", "string2");
console.log(newStr)
// "string2 string2 string2"
simplest form as below
if you need to replace only first occurrence
var newString = oldStr.replace('want', 'dont want');
if you want ot repalce all occurenace
var newString = oldStr.replace(want/g, 'dont want');
Added a method replace_in_javascript which will satisfy your requirement. Also found that you are writing a string "new_text" in document.write() which is supposed to refer to a variable new_text.
let replace_in_javascript= (replaceble, replaceTo, text) => {
return text.replace(replaceble, replaceTo)
}
var text = "this is some sample text that i want to replace";
var new_text = replace_in_javascript("want", "dont want", text);
document.write(new_text);