Str replace in javascript

Str replace in javascript DEFAULT

How to replace all occurrences of a string in JavaScript

Update:

It's somewhat late for an update, but since I just stumbled on this question, and noticed that my previous answer is not one I'm happy with. Since the question involved replaceing a single word, it's incredible nobody thought of using word boundaries ()

This is a simple regex that avoids replacing parts of words in most cases. However, a dash is still considered a word boundary. So conditionals can be used in this case to avoid replacing strings like :


basically, this question is the same as the question here: Javascript replace " ' " with " '' "

@Mike, check the answer I gave there... regexp isn't the only way to replace multiple occurrences of a subsrting, far from it. Think flexible, think split!

Alternatively, to prevent replacing word parts -which the approved answer will do, too! You can get around this issue using regular expressions that are, I admit, somewhat more complex and as an upshot of that, a tad slower, too:

The output is the same as the accepted answer, however, using the /cat/g expression on this string:

Oops indeed, this probably isn't what you want. What is, then? IMHO, a regex that only replaces 'cat' conditionally. (ie not part of a word), like so:

My guess is, this meets your needs. It's not fullproof, of course, but it should be enough to get you started. I'd recommend reading some more on these pages. This'll prove useful in perfecting this expression to meet your specific needs.

http://www.javascriptkit.com/jsref/regexp.shtml

http://www.regular-expressions.info


Final addition:

Given that this question still gets a lot of views, I thought I might add an example of used with a callback function. In this case, it dramatically simplifies the expression and provides even more flexibility, like replacing with correct capitalisation or replacing both and in one go:

Sours: https://stackoverflow.com/questions/1144783/how-to-replace-all-occurrences-of-a-string-in-javascript

String.prototype.replace()

The method returns a new string with some or all matches of a replaced by a . The can be a string or a , and the can be a string or a function to be called for each match. If  is a string, only the first occurrence will be replaced.

The original string is left unchanged.

Syntax

Parameters

(pattern)

A object or literal. The match or matches are replaced with or the value returned by the specified .

A that is to be replaced by . It is treated as a literal string and is not interpreted as a regular expression. Only the first occurrence will be replaced.

(replacement)

The that replaces the substring specified by the specified or parameter. A number of special replacement patterns are supported; see the "Specifying a string as a parameter" section below.

If is an empty string, then the substring given by , or the matches for , are removed (rather then being replaced).

(replacement)

A function to be invoked to create the new substring to be used to replace the matches to the given or . The arguments supplied to this function are described in the "Specifying a function as a parameter" section below.

Return value

A new string, with some or all matches of a pattern replaced by a replacement.

Description

This method does not change the calling object. It returns a new string.

To perform a global search and replace, include the switch in the regular expression.

Specifying a string as a parameter

The replacement string can include the following special replacement patterns:

PatternInserts
Inserts a .
Inserts the matched substring.
Inserts the portion of the string that precedes the matched substring.
Inserts the portion of the string that follows the matched substring.
Where is a positive integer less than 100, inserts the th parenthesized submatch string, provided the first argument was a object. Note that this is -indexed. If a group is not present (e.g., if group is 3), it will be replaced as a literal (e.g., ).
Where is a capturing group name. If the group is not in the match, or not in the regular expression, or if a string was passed as the first argument to instead of a regular expression, this resolves to a literal (e.g., ). Only available in browser versions supporting named capturing groups.

Specifying a function as a parameter

You can specify a function as the second parameter. In this case, the function will be invoked after the match has been performed. The function's result (return value) will be used as the replacement string. (Note: The above-mentioned special replacement patterns do not apply in this case.)

Note that the function will be invoked multiple times for each full match to be replaced if the regular expression in the first parameter is global.

The arguments to the function are as follows:

Possible nameSupplied value
The matched substring. (Corresponds to above.)
The nth string found by a parenthesized capture group (including named capturing groups), provided the first argument to was a object. (Corresponds to , , etc. above.) For example, if , was given, is the match for , and  for .
The offset of the matched substring within the whole string being examined. (For example, if the whole string was , and the matched substring was , then this argument will be .)
The whole string being examined.
In browser versions supporting named capturing groups, will be an object whose keys are the used group names, and whose values are the matched portions ( if not matched).

(The exact number of arguments depends on whether the first argument is a object—and, if so, how many parenthesized submatches it specifies.)

The following example will set to :

Examples

Defining the regular expression in replace()

In the following example, the regular expression is defined in and includes the ignore case flag.

This logs .

Note: See this guide for more explanations about regular expressions.

Using global and ignore with replace()

Global replace can only be done with a regular expression. In the following example, the regular expression includes the global and ignore case flags which permits to replace each occurrence of in the string with .

This logs .

Switching words in a string

The following script switches the words in the string. For the replacement text, the script uses capturing groups and the and replacement patterns.

This logs .

Using an inline function that modifies the matched characters

In this example, all occurrences of capital letters in the string are converted to lower case, and a hyphen is inserted just before the match location. The important thing here is that additional operations are needed on the matched item before it is given back as a replacement.

The replacement function accepts the matched snippet as its parameter, and uses it to transform the case and concatenate the hyphen before returning.

Given , this returns .

Because we want to further transform the result of the match before the final substitution is made, we must use a function. This forces the evaluation of the match prior to the method. If we had tried to do this using the match without a function, the would have no effect.

This is because would first be evaluated as a string literal (resulting in the same ) before using the characters as a pattern.

Replacing a Fahrenheit degree with its Celsius equivalent

The following example replaces a Fahrenheit degree with its equivalent Celsius degree. The Fahrenheit degree should be a number ending with . The function returns the Celsius number ending with . For example, if the input number is , the function returns . If the number is , the function returns .

The regular expression checks for any number that ends with . The number of Fahrenheit degree is accessible to the function through its second parameter, . The function sets the Celsius number based on the Fahrenheit degree passed in a string to the function. then returns the Celsius number. This function approximates Perl's flag.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

Sours: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace
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JavaScript string.replace() Method

Below is the example of the string.replace() Method. 
 

javascript

 

GfG

The string.replace() is an inbuilt method in JavaScript which is used to replace a part of the given string with some another string or a regular expression. The original string will remain unchanged.
Syntax: 
 

str.replace(A, B)

Parameters: Here the parameter A is regular expression and B is a string which will replace the content of the given string. 
Return Values: It returns a new string with replaced items.
JavaScript code to show the working of this method: 
Code #1: 
Here the contents of the string GeeksForGeeks will be replaced with gfg. 
 

javascript

 

 

 

 

Output: 
 

gfg is a CS portal

Code #2: 
 



javascript

 

 

 

 

 

Output: 
 

gfg is a CS portal

Supported Browsers: 
 

  • Google Chrome 1 and above
  • Edge 12 and above
  • Firefox 1 and above
  • Internet Explorer 5.5 and above
  • Opera 4 and above
  • Safari 1 and above

 

Hey geek! The constant emerging technologies in the world of web development always keeps the excitement for this subject through the roof. But before you tackle the big projects, we suggest you start by learning the basics. Kickstart your web development journey by learning JS concepts with ourJavaScript Course. Now at it’s lowest price ever!




Sours: https://www.geeksforgeeks.org/javascript-string-replace-method/
Search and replace using javascript String.replace()

JavaScript String replace() Method

next →← prev

The JavaScript string replace() method is used to replace a part of a given string with a new substring. This method searches for specified regular expression in a given string and then replace it if the match occurs.

We can use global search modifier with replace() method to replace all the match elements otherwise the method replace only first match. JavaScript also provides ignore flag to make the method case-insensitive.

Syntax

The replace() method is represented by the following syntax:

Parameter

originalstr - It represents the string to be searched and replaced.

Newstr - It represents the new string that replaced with the searched string.

Return

It returns the new string with the specified replacement.

JavaScript String replace() Method Example

Let's see some examples of replace() method.

Example 1

Let's see a simple example to replace a substring.

Test it Now

Output:

Example 2

In this example, we will replace a regular expression using global search modifier.

Test it Now

Output:

Learn AngularJS on Javatpoint. AngularJS is a well-known JavaScript framework.

Example 3

In this example, we will replace a regular expression without using global search.

Test it Now

Output:

Learn AngularJS on Javatpoint. Node.js is a well-known JavaScript framework

Example 4

In this example, we will see that replace() method is case-sensitive.

Test it Now

Output:

Learn Node.js on Javatpoint. Node.js is a well-known JavaScript framework.

Example 5

We can ignore case-sensitive behaviour of replace() method by using ignore flag modifier. Let's understand with the help of example:

Test it Now

Output:

Learn AngularJS on Javatpoint. AngularJS is a well-known JavaScript framework.

Next TopicJavaScript String



← prevnext →



Sours: https://www.javatpoint.com/javascript-string-replace-method

Replace javascript str in

JavaScript String replace()

❮ PreviousJavaScript String ReferenceNext ❯

Example

Return a string where "Microsoft" is replaced with "W3Schools":

let str = "Visit Microsoft!";
str.replace("Microsoft", "W3Schools");

Try it Yourself »

More "Try it Yourself" examples below.


Definition and Usage

The method searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced.

Note: If you are replacing a value (and not a regular expression), only the first instance of the value will be replaced. To replace all occurrences of a specified value, use the global (g) modifier (see "More Examples" below).

Read more about regular expressions in our RegExp Tutorial and our RegExp Object Reference.

does not change the original string.


Browser Support

is an ES1 feature (JavaScript 1999).

It is fully supported in all browsers:

ChromeIEEdgeFirefoxSafariOpera
YesYesYesYesYesYes

Syntax

string.replace(searchvalue, newvalue)

Parameter Values

ParameterDescription
searchvalueRequired. The value, or regular expression, that will be replaced by the new value
newvalueRequired. The value to replace the search value with


Technical Details

Return Value:A new String, where the specified value(s) has been replaced by the new value
JavaScript Version:ECMAScript 1

More Examples

Example

Perform a global replacement:

let str = "Mr Blue has a blue house and a blue car";
str.replace(/blue/g, "red");

Try it Yourself »

Example

Perform a global, case-insensitive replacement:

let str = "Mr Blue has a blue house and a blue car";
str.replace(/blue/gi, "red");

Try it Yourself »

Example

Using a function to return the replacement text:

let str = "Mr Blue has a blue house and a blue car";
str.replace(/blue|house|car/gi, function (x) {
  return x.toUpperCase();
});

Try it Yourself »

Related Pages

String Tutorial

String Methods

String Search


❮ PreviousJavaScript String ReferenceNext ❯


Sours: https://www.w3schools.com/jsref/jsref_replace.asp
JavaScript String Replace - Case Insensitive

String.prototype.replaceAll()

You can specify a function as the second parameter. In this case, the function will be invoked after the match has been performed. The function's result (return value) will be used as the replacement string. (Note: The above-mentioned special replacement patterns do not apply in this case.)

Note that if the first argument of an invocation is a object or regular expression literal, the function will be invoked multiple times.

The arguments to the function are as follows:

Possible nameSupplied value
The matched substring. (Corresponds to above.)
The nth string found by a parenthesized capture group, provided the first argument to was a object. (Corresponds to , , etc. above.) For example, if , was given, is the match for , and  for .
The offset of the matched substring within the whole string being examined. (For example, if the whole string was , and the matched substring was , then this argument will be .)
The whole string being examined.

(The exact number of arguments depends on whether the first argument is a object—and, if so, how many parenthesized submatches it specifies.)

Examples

Using replaceAll

Non-global regex throws

When using a regular expression search value, it must be global. This won't work:

This will work:

Specifications

Browser compatibility

BCD tables only load in the browser

See also

Sours: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replaceAll

Similar news:

3 Ways To Replace All String Occurrences in JavaScript

There’s no easy way to replace all string occurrences in JavaScript. Java, which had served an inspiration for JavaScript in the first days, has the method on strings since 1995!

In this post, you’ll learn how to replace all string occurrences in JavaScript by splitting and joining a string, and combined with a global regular expression.

Moreover, you’ll read about the new proposal string.replaceAll() (at stage 4) that brings the replace all method to JavaScript strings. This is the most convenient approach.

1. Splitting and joining an array

If you google how to “replace all string occurrences in JavaScript”, most likely the first approach you’d find is to use an intermediate array.

Here’s how it works:

  1. Split the into by the string:

javascript

  1. Then join the pieces putting the string in between:

javascript

For example, let’s replace all spaces with hyphens in string:

javascript

splits the string into pieces: .

Then the pieces are joined by inserting in between them, which results in the string .

Here’s a generalized helper function that uses splitting and joining approach:

javascript

This approach requires transforming the string into an array, and then back into a string. Let’s continue looking for better alternatives.

2. replace() with a global regular expression

The string method searches and replaces the occurrences of the regular expression with string.

To make the method replace all occurrences of the pattern you have to enable the global flag on the regular expression:

  1. Append after at the end of regular expression literal:
  2. Or when using a regular expression constructor, add to the second argument:

Let’s replace all occurrences of with :

javascript

The regular expression literal (note the global flag) matches the space .

replaces all matches of with , which results in .

You can easily make case insensitive replaces by adding flag to the regular expression:

javascript

The regular expression performs a global case-insensitive search (note and flags). matches , as well as .

Invoking replaces all matches of substrings with .

2.1 Regular expression from a string

When the regular expression is created from a string, you have to escape the characters because they have special meaning within the regular expression.

Because of that, the special characters are a problem when you’d like to make replace all operation. Here’s an example:

javascript

The above snippet tries to transform the search string into a regular expression. But is an invalid regular expression, thus is thrown.

Escaping the character solves the problem.

Nevertheless, does it worth escaping the search string using a function like escapeRegExp() to be used as a regular expression? Most likely not.

2.2 replace() with a string

If the first argument of is a string, then the method replaces only the first occurrence of :

javascript

replaces only the first appearance of a space.

3. replaceAll() method

Finally, the method replaces all appearances of string with .

Let’s replace all occurrences of with :

javascript

replaces all occurrences of string with .

is the best way to replace all string occurrences in a string

Note that currently, the method support in browsers is limited, and you might require a polyfill.

3.1 The difference between replaceAll() and replace()

The string methods and work the same way, expect 2 things:

  1. If argument is a string, replaces all occurrences of with , while only the first occurence
  2. If argument is a non-global regular expression, then throws a exception.

4. Key takeaway

The primitive approach to replace all occurrences is to split the string into chunks by the search string, the join back the string placing the replace string between chunks: . This approach works, but it’s hacky.

Another approach is to use with a regular expression having the global flag enabled.

Unfortunately, you cannot easily generate regular expressions from a string at runtime, because the special characters of regular expressions have to be escaped. And dealing with a regular expression for a simple replacement of strings is overwhelming.

Finally, the new string method replaces all string occurrences. The method is a proposal at stage 4, and hopefully, it will land in a new JavaScript standard pretty soon.

My recommendation is to use to replace strings.

What other ways to replace all string occurrences do you know? Please share in a comment below!

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