I am trying to change specific word in a string with something else. For example, I want to change 'John' in let name = 'Hi, my name is John.'; to 'Jack'.
I know how to split a string by words or characters. I also know how to remove commas, periods, and other symbols in a string. However, if I split the given string with a separator (" "), I will have 'John.' which I do not want. (I know I can switch 'John.' with 'Jack.' but assume that I have an key and value pairs in an object and I am using the values which are names {Father: Jack, Mother: Susan, ...}
I don't know how to separate a string word by word including commas and periods.
For example, if I was given an input which is a string:
'Hi, my name is John.'
I want to split the input as below:
['Hi', ',', 'my', 'name', 'is', 'John', '.']
Does anyone know how to do it?
Below is the challenge I am working on.
Create a function censor that accepts no arguments. censor will return a function that will accept either two strings, or one string. When two strings are given, the returned function will hold onto the two strings as a pair, for future use. When one string is given, the returned function will return the same string, except all instances of a first string (of a saved pair) will be replaced with the second string (of a saved pair).
//Your code here
const changeScene = censor();
changeScene('dogs', 'cats');
changeScene('quick', 'slow');
console.log(changeScene('The quick, brown fox jumps over the lazy dogs.')); // should log: 'The slow, brown fox jumps over the lazy cats.'
I think your real question is "How do I replace a substring with another string?"
Checkout the replace method:
let inputString = "Hi, my name is John.";
let switch1 = ["John", "Jack"];
let switched = inputString.replace(switch1[0], switch1[1]);
console.log(switched); // Hi, my name is Jack.
UPDATE: If you want to get ALL occurrences (g), be case insensitive (i), and use boundaries so that it isn't a word within another word (\\b), you can use RegExp:
let inputString = "I'm John, or johnny, but I prefer john.";
let switch1 = ["John", "Jack"];
let re = new RegExp(`\\b${switch1[0]}\\b`, 'gi');
console.log(inputString.replace(re, switch1[1])); // I'm Jack, or johnny, but I prefer Jack.
You can Try This ...
var string = 'Hi, my name is John.';
//var arr = string.split(/,|\.| /);
var arr = string.split(/([,.\s])/);
console.log(arr);
Using 'Hi, my name is John.'.split(/[,. ]/); will do the job. It will split commas and periods and spaces.
Edit: For those who want to keep the comma and period, here is my wildly inefficient method.
var str = 'Hi, my name is John.'
str = str.replace('.', 'period');
str = str.replace(',', 'comma');
str = str.split(/[,. ]/);
for (var i = 0; i < str.length; i++) {
if (str[i].indexOf('period') > -1) {
str[i] = str[i].replace('period', '');
str.splice(i+1, 0, ".");
} else if (str[i].indexOf('comma') > -1) {
str[i] = str[i].replace('comma', '');
str.splice(i+1, 0, ",");
}
}
console.log(str);
lets suppose i have string
var string = "$-20455.00"
I am trying to swap first two characters of a string. I was thinking to split it and make an array and then replacing it, but is there any other way? Also, I am not clear how can I achieve it using arrays? if I have to use arrays.
var string = "-$20455.00"
How can I achieve this?
You can use the replace function in Javascript.
var string = "$-20455.00"
string = string.replace(/^.{2}/g, 'rr');
Here is jsfiddle: https://jsfiddle.net/aoytdh7m/33/
You dont have to use arrays. Just do this
string[1] + string[0] + string.slice(2)
You can split to an array, and then reverse the first two characters and join the pieces together again
var string = "$-20455.00";
var arr = string.split('');
var result = arr.slice(0,2).reverse().concat(arr.slice(2)).join('');
document.body.innerHTML = result;
try using the "slice" method and string concatenation:
stringpart1 = '' //fill in whatever you want to replace the first two characters of the first string with here
string2 = stringpart1 + string.slice(1)
edit: I now see what you meant by "swap". I thought you meant "swap in something else". Vlad's answer is best to just switch the first and the second character.
Note that string[0] refers to the first character in the string, and string[1] to the second character, and so on, because code starts counting at 0.
var string = "$-20455.00";
// Reverse first two characters
var reverse = string.slice(0,2).split('').reverse().join('');
// Concat again with renaming string
var result= reverse.concat(string.slice(2));
document.body.innerHTML = result;
let finalStr = string[1] + string[0] + string.slice(2); //this will give you the result
I have a text which goes like this...
var string = '~a=123~b=234~c=345~b=456'
I need to extract the string such that it splits into
['~a=123~b=234~c=345','']
That is, I need to split the string with /b=.*/ pattern but it should match the last found pattern. How to achieve this using RegEx?
Note: The numbers present after the equal is randomly generated.
Edit:
The above one was just an example. I did not make the question clear I guess.
Generalized String being...
<word1>=<random_alphanumeric_word>~<word2>=<random_alphanumeric_word>..~..~..<word2>=<random_alphanumeric_word>
All have random length and all wordi are alphabets, the whole string length is not fixed. the only text known would be <word2>. Hence I needed RegEx for it and pattern being /<word2>=.*/
This doesn't sound like a job for regexen considering that you want to extract a specific piece. Instead, you can just use lastIndexOf to split the string in two:
var lio = str.lastIndexOf('b=');
var arr = [];
var arr[0] = str.substr(0, lio);
var arr[1] = str.substr(lio);
http://jsfiddle.net/NJn6j/
I don't think I'd personally use a regex for this type of problem, but you can extract the last option pair with a regex like this:
var str = '~a=123~b=234~c=345~b=456';
var matches = str.match(/^(.*)~([^=]+=[^=]+)$/);
// matches[1] = "~a=123~b=234~c=345"
// matches[2] = "b=456"
Demo: http://jsfiddle.net/jfriend00/SGMRC/
Assuming the format is (~, alphanumeric name, =, and numbers) repeated arbitrary number of times. The most important assumption here is that ~ appear once for each name-value pair, and it doesn't appear in the name.
You can remove the last token by a simple replacement:
str.replace(/(.*)~.*/, '$1')
This works by using the greedy property of * to force it to match the last ~ in the input.
This can also be achieved with lastIndexOf, since you only need to know the index of the last ~:
str.substring(0, (str.lastIndexOf('~') + 1 || str.length() + 1) - 1)
(Well, I don't know if the code above is good JS or not... I would rather write in a few lines. The above is just for showing one-liner solution).
A RegExp that will give a result that you may could use is:
string.match(/[a-z]*?=(.*?((?=~)|$))/gi);
// ["a=123", "b=234", "c=345", "b=456"]
But in your case the simplest solution is to split the string before extract the content:
var results = string.split('~'); // ["", "a=123", "b=234", "c=345", "b=456"]
Now will be easy to extract the key and result to add to an object:
var myObj = {};
results.forEach(function (item) {
if(item) {
var r = item.split('=');
if (!myObj[r[0]]) {
myObj[r[0]] = [r[1]];
} else {
myObj[r[0]].push(r[1]);
}
}
});
console.log(myObj);
Object:
a: ["123"]
b: ["234", "456"]
c: ["345"]
(?=.*(~b=[^~]*))\1
will get it done in one match, but if there are duplicate entries it will go to the first. Performance also isn't great and if you string.replace it will destroy all duplicates. It would pass your example, but against '~a=123~b=234~c=345~b=234' it would go to the first 'b=234'.
.*(~b=[^~]*)
will run a lot faster, but it requires another step because the match comes out in a group:
var re = /.*(~b=[^~]*)/.exec(string);
var result = re[1]; //~b=234
var array = string.split(re[1]);
This method will also have the with exact duplicates. Another option is:
var regex = /.*(~b=[^~]*)/g;
var re = regex.exec(string);
var result = re[1];
// if you want an array from either side of the string:
var array = [string.slice(0, regex.lastIndex - re[1].length - 1), string.slice(regex.lastIndex, string.length)];
This actually finds the exact location of the last match and removes it regex.lastIndex - re[1].length - 1 is my guess for the index to remove the ellipsis from the leading side, but I didn't test it so it might be off by 1.
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);
I'm trying to write a "suggestion search box" and I cannot find a solution that allows to highlight a substring with javascript keeping the original case.
For example if I search for "ca" I search server side in a case insensitive mode and I have the following results:
Calculator
calendar
ESCAPE
I would like to view the search string in all the previous words, so the result should be:
Calculator
calendar
ESCAPE
I tried with the following code:
var reg = new RegExp(querystr, 'gi');
var final_str = 'foo ' + result.replace(reg, '<b>'+querystr+'</b>');
$('#'+id).html(final_str);
But obviously in this way I loose the original case!
Is there a way to solve this problem?
Use a function for the second argument for .replace() that returns the actual matched string with the concatenated tags.
Try it out: http://jsfiddle.net/4sGLL/
reg = new RegExp(querystr, 'gi');
// The str parameter references the matched string
// --------------------------------------v
final_str = 'foo ' + result.replace(reg, function(str) {return '<b>'+str+'</b>'});
$('#' + id).html(final_str);
JSFiddle Example with Input: https://jsfiddle.net/pawmbude/
ES6 version
const highlight = (needle, haystack) =>
haystack.replace(
new RegExp(needle, 'gi'),
(str) => `<strong>${str}</strong>`
);
nice results with
function str_highlight_text(string, str_to_highlight){
var reg = new RegExp(str_to_highlight, 'gi');
return string.replace(reg, function(str) {return '<span style="background-color:#ffbf00;color:#fff;"><b>'+str+'</b></span>'});
}
and easier to remember...
thx to user113716: https://stackoverflow.com/a/3294644/2065594
While the other answers so far seem simple, they can't be really used in many real world cases as they don't handle proper text HTML escaping and RegExp escaping. If you want to highlight every possible snippet, while escaping the text properly, a function like that would return all elements you should add to your suggestions box:
function highlightLabel(label, term) {
if (!term) return [ document.createTextNode(label) ]
const regex = new RegExp(term.replace(/[\\^$*+?.()|[\]{}]/g, '\\$&'), 'gi')
const result = []
let left, match, right = label
while (match = right.match(regex)) {
const m = match[0], hl = document.createElement('b'), i = match.index
hl.innerText = m
left = right.slice(0, i)
right = right.slice(i + m.length)
result.push(document.createTextNode(left), hl)
if (!right.length) return result
}
result.push(document.createTextNode(right))
return result
}
string.replace fails in the general case. If you use .innerHTML, replace can replace matches in tags (like a tags). If you use .innerText or .textContent, it will remove any tags there were previously in the html. More than that, in both cases it damages your html if you want to remove the highlighting.
The true answer is mark.js (https://markjs.io/). I just found this - it is what I have been searching for for such a long time. It does just what you want it to.
I do the exact same thing.
You need to make a copy.
I store in the db a copy of the real string, in all lower case.
Then I search using a lower case version of the query string or do a case insensitive regexp.
Then use the resulting found start index in the main string, plus the length of the query string, to highlight the query string within the result.
You can not use the query string in the result since its case is not determinate. You need to highlight a portion of the original string.
.match() performs case insensitive matching and returns an array of the matches with case intact.
var matches = str.match(queryString),
startHere = 0,
nextMatch,
resultStr ='',
qLength = queryString.length;
for (var match in matches) {
nextMatch = str.substr(startHere).indexOf(match);
resultStr = resultStr + str.substr(startHere, nextMatch) + '<b>' + match + '</b>';
startHere = nextMatch + qLength;
}
I have found a easiest way to achieve it. JavaScript regular expression remembers the string it matched. This feature can be used here.
I have modified the code a bit.
reg = new RegExp("("+querystr.trim()+")", 'gi');
final_str = 'foo ' + result.replace(reg, "<b>&1</b>");
$('#'+id).html(final_str);
Highlight search term and anchoring to first occurence - Start
function highlightSearchText(searchText) {
var innerHTML = document.documentElement.innerHTML;
var replaceString = '<mark>'+searchText+'</mark>';
var newInnerHtml = this.replaceAll(innerHTML, searchText, replaceString);
document.documentElement.innerHTML = newInnerHtml;
var elmnt = document.documentElement.getElementsByTagName('mark')[0]
elmnt.scrollIntoView();
}
function replaceAll(str, querystr, replace) {
var reg = new RegExp(querystr, 'gi');
var final_str = str.replace(reg, function(str) {return '<mark>'+str+'</mark>'});
return final_str
}
Highlight search term and anchoring to first occurence - End