如何替换字符串的所有出现?
给定一个字符串:
string = "Test abc test test abc test test test abc test test abc";
这似乎仅删除上面字符串中的 abc
的第一次出现:
string = string.replace('abc', '');
如何替换 all 出现它?
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截至2020年8月: 现代浏览器对 =“ https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/string/replaceall/replaceall” rel =“ noreferrer”>
string.replaceall(replaceall(Replaceall() /a>由ecmascript 2021语言规范定义。
对于较旧/旧的浏览器:
这是如何演变的:
回答评论“如果'abc'作为变量是什么
? stackoverflow.com/users/49153/click-upvote"> click upvote 的评论,您可以更简化它:
注意:正则表达式包含特殊(meta)字符,以及AS在
中盲目地通过一个参数在上面找到
函数而无需预处理以逃脱这些字符是危险的。 mozilla开发人员网络's javaScript指南正式表达式指南,它们呈现以下实用程序功能(至少已更改了至少已更改由于此答案最初是两次,因此请确保检查MDN站点是否有潜在的更新):因此,为了使
felpaceAll()
函数上述更安全,可以将其修改为以下内容。还包括Escaperegexp
:As of August 2020: Modern browsers have support for the
String.replaceAll()
method defined by the ECMAScript 2021 language specification.For older/legacy browsers:
Here is how this answer evolved:
In response to comment "what's if 'abc' is passed as a variable?":
In response to Click Upvote's comment, you could simplify it even more:
Note: Regular expressions contain special (meta) characters, and as such it is dangerous to blindly pass an argument in the
find
function above without pre-processing it to escape those characters. This is covered in the Mozilla Developer Network's JavaScript Guide on Regular Expressions, where they present the following utility function (which has changed at least twice since this answer was originally written, so make sure to check the MDN site for potential updates):So in order to make the
replaceAll()
function above safer, it could be modified to the following if you also includeescapeRegExp
:为了完整,我必须考虑应该使用哪种方法来执行此操作。如本页面上的其他答案所建议的,基本上有两种方法可以做到这一点。
注意:通常,通常不建议在JavaScript中扩展内置原型。我仅出于插图的目的而作为字符串原型上的扩展名提供,显示了
String
内置原型的假设标准方法的不同实现。基于正则表达式的实施
拆分和加入(功能)实现对
正则表达方式在效率方面的工作方式不太了解,我倾向于倾向于拆分并在过去而无需考虑性能的情况下加入实施。当我确实想知道哪个更有效,而从哪个边距开始时,我以此为借口找出答案。
在我的Chrome Windows  8机器上,基于正则表达式的实现是最快的,拆分,加入实现速度慢了53%。这意味着我使用的lorem ipsum输入的正则表达式是两倍。
查看此 基准 互相运行这两个实现。
如@thomasleduc和其他其他评论中所述,如果
search
包含某些保留为正式表达式中的特殊字符。该实现假设呼叫者将事先逃脱字符串,或者仅通过 正则表达式 (mdn)。MDN还提供了一种实现,以逃避我们的字符串。如果它也标准化为
Regexp.Escape(str)
,那将是很好的,但是,不存在:我们可以在我们的
字符串中调用
实现,但是,我不确定这会影响性能有多大(即使对于不需要逃脱的字符串,也可能像所有字母数字字符串一样)。Escaperegexp
。 prototype.replaceallFor the sake of completeness, I got to thinking about which method I should use to do this. There are basically two ways to do this as suggested by the other answers on this page.
Note: In general, extending the built-in prototypes in JavaScript is generally not recommended. I am providing as extensions on the String prototype simply for purposes of illustration, showing different implementations of a hypothetical standard method on the
String
built-in prototype.Regular Expression Based Implementation
Split and Join (Functional) Implementation
Not knowing too much about how regular expressions work behind the scenes in terms of efficiency, I tended to lean toward the split and join implementation in the past without thinking about performance. When I did wonder which was more efficient, and by what margin, I used it as an excuse to find out.
On my Chrome Windows 8 machine, the regular expression based implementation is the fastest, with the split and join implementation being 53% slower. Meaning the regular expressions are twice as fast for the lorem ipsum input I used.
Check out this benchmark running these two implementations against each other.
As noted in the comment below by @ThomasLeduc and others, there could be an issue with the regular expression-based implementation if
search
contains certain characters which are reserved as special characters in regular expressions. The implementation assumes that the caller will escape the string beforehand or will only pass strings that are without the characters in the table in Regular Expressions (MDN).MDN also provides an implementation to escape our strings. It would be nice if this was also standardized as
RegExp.escape(str)
, but alas, it does not exist:We could call
escapeRegExp
within ourString.prototype.replaceAll
implementation, however, I'm not sure how much this will affect the performance (potentially even for strings for which the escape is not needed, like all alphanumeric strings).在最受欢迎的浏览器的最新版本中,您可以使用
替换
如下所示:
但是检查我可以首先使用或其他兼容性表,以确保您是浏览器定位首先增加了对其的支持。
对于node.js以及与较旧/非电流浏览器的兼容性:
注意:不要在performance关键代码中使用以下解决方案。
作为简单文字字符串的正则表达式的替代方案,您可以使用
一般模式
在某些情况下比使用
替换
和正则表达式更快,但是在现代浏览器中似乎不再是这种情况。基准: https://jsben.ch/tzyzj
结论:
如果您有绩效 - 关键用例(例如,处理数百个字符串),使用正则表达方法。但是对于大多数典型的用例,这是值得不必担心特殊角色的。
In the latest versions of most popular browsers, you can use
replaceAll
as shown here:
But check Can I use or another compatibility table first to make sure the browsers you're targeting have added support for it first.
For Node.js and compatibility with older/non-current browsers:
Note: Don't use the following solution in performance critical code.
As an alternative to regular expressions for a simple literal string, you could use
The general pattern is
This used to be faster in some cases than using
replaceAll
and a regular expression, but that doesn't seem to be the case anymore in modern browsers.Benchmark: https://jsben.ch/TZYzj
Conclusion:
If you have a performance-critical use case (e.g., processing hundreds of strings), use the regular expression method. But for most typical use cases, this is well worth not having to worry about special characters.
这些是最常见和可读的方法。
方法1:
方法2:
方法3:
方法4:
输出:
These are the most common and readable methods.
Method 1:
Method 2:
Method 3:
Method 4:
Output:
使用单词边界(
\ b
),这是一个简单的正则义务,避免在大多数情况下更换单词的一部分。但是,Dash
-
仍然被视为单词边界。因此,可以在这种情况下使用条件,以避免替换诸如cool-cat
之类的字符串:基本上,此问题与这里的问题相同:
replace''''''with javascript
子弦的多次出现,远非如此。思考灵活,想想分裂!
另外,为了防止更换单词零件 - 批准的答案也将做到!您可以使用我承认的正则表达式解决此问题,这些表达式更为复杂,并且作为其中的结果,也会慢一点:
输出与可接受的答案但是,使用
/cat/g
在此字符串上的表达:确实,这可能不是您想要的。那是什么?恕我直言,只有有条件地替代“猫”的正则(即,不是单词的一部分),就像这样:
我的猜测是,这满足了您的需求。当然,这不是万无一失的,但是应该足以让您开始。我建议您阅读有关这些页面的更多信息。这将证明在完善此表达式以满足您的特定需求时很有用。
regexp(正则表达式)对象
这是
.replace的示例。
与回调功能一起使用。在这种情况下,它极大地简化了表达式和的灵活性,例如用正确的资本化替换或同时替换cat
cat> cats :Use word boundaries (
\b
)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 likecool-cat
:Basically, this question is the same as the question here:
Replace " ' " with " '' " in JavaScript
Regexp isn't the only way to replace multiple occurrences of a substring, 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 (i.e., not part of a word), like so:
My guess is, this meets your needs. It's not foolproof, 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.
RegExp (regular expression) object
Regular-Expressions.info
Here is an example of
.replace
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 bothcat
andcats
in one go:与全球正则表达式匹配:
Match against a global regular expression:
或尝试此答案:
或:
编辑:澄清
replaceAll
可用性fellaceall
方法添加到string
的原型。这意味着它将适用于所有字符串对象/文字。例子:
Or try the
replaceAll
method, as recommended in this answer:or:
EDIT: Clarification about
replaceAll
availabilityThe
replaceAll
method is added toString
's prototype. This means it will be available for all string objects/literals.Example:
使用正则表达式:
Use a regular expression:
今天的表现
今天27.12.2019我在
结论
str.replace(/abc/g,'');
( c )是所有字符串的良好跨浏览器快速解决方案。split-join
( a,b )或替换
( c,d )的解决方案是我还创建了自己的解决方案。看来目前是做问题作业的最短的:
详细信息
测试是在Chrome 79.0,Safari 13.0.4和Firefox 71.0(64位)上进行的。测试
RA
和RB
使用递归。结果短字符串 - 55个字符
可以在计算机上运行测试在这里。 Chrome的结果:
长字符串:275 000个字符
递归解决方案 ra 和 rb 给出
1M字符的最大呼叫堆栈大小,甚至可以打破Chrome
我尝试为其他解决方案执行1M字符的测试,但是 e,f,g,g,h 都这样做浏览器要求我打破脚本的很多时间,所以我将测试字符串缩小到275K字符。您可以在计算机上运行测试在这里。 Chrome
测试中使用的代码
Performance
Today 27.12.2019 I perform tests on macOS v10.13.6 (High Sierra) for the chosen solutions.
Conclusions
str.replace(/abc/g, '');
(C) is a good cross-browser fast solution for all strings.split-join
(A,B) orreplace
(C,D) are fastwhile
(E,F,G,H) are slow - usually ~4 times slower for small strings and about ~3000 times (!) slower for long stringsI also create my own solution. It looks like currently it is the shortest one which does the question job:
Details
The tests were performed on Chrome 79.0, Safari 13.0.4 and Firefox 71.0 (64 bit). The tests
RA
andRB
use recursion. ResultsShort string - 55 characters
You can run tests on your machine HERE. Results for Chrome:
Long string: 275 000 characters
The recursive solutions RA and RB gives
For 1M characters they even break Chrome
I try to perform tests for 1M characters for other solutions, but E,F,G,H takes so much time that browser ask me to break script so I shrink test string to 275K characters. You can run tests on your machine HERE. Results for Chrome
Code used in tests
循环它直到数字出现为0,因此:
Loop it until number occurrences comes to 0, like this:
这是最快的版本,不使用正则表达式。
修订后的jsperf
几乎 很快作为拆分和加入方法。
正如这里的评论中指出的那样,如果您的
省略
变量包含plot
,如:replaceAceAll(“ string”,“ s”,“,” SS”)
,因为它将始终能够替换单词的另一个出现。我的递归替换上还有另一个带有变体的jsperf,它的变化更快( http:// jsperf.com/replace-all-vs-split-join/12 )!
This is the fastest version that doesn't use regular expressions.
Revised jsperf
It is almost twice as fast as the split and join method.
As pointed out in a comment here, this will not work if your
omit
variable containsplace
, as in:replaceAll("string", "s", "ss")
, because it will always be able to replace another occurrence of the word.There is another jsperf with variants on my recursive replace that go even faster (http://jsperf.com/replace-all-vs-split-join/12)!
如果您想找到的已经在字符串中,并且您没有正则逃逸者方便,则可以使用Join/Split:
If what you want to find is already in a string, and you don't have a regex escaper handy, you can use join/split:
当然在 2021 正确的答案是:
string.prototype.replaceall()
如果您不想处理 + noreferrer“> regexp 。
但是,如果浏览器从2020年开始?
在这种情况下,我们需要 (强迫较旧的浏览器支持新功能)(我认为需要几年的时间)。
我找不到答案中完全正确的方法。因此,我建议将此功能定义为多填充。
我建议的
替换
polyfill的建议选项:fellaceAll
polyfill(带有global-flag错误)(更有原则的版本)fellaceall
polyfill(处理Global-flag(处理Global-Flag) (我的第一个偏爱) - 为什么?第一个偏好):
尝试:
浏览器支持:
结果与本机替换相同,如果第一个参数输入为:
null
,未定义代码> REGEXP
,号码
,字符串
,...ref: 22.1.3.19 string.prototype.replaceall(searchValue,repenterValue)
+
重要说明:正如一些专业人士提到的那样,答案中建议的许多递归功能都会返回错误的结果。 (尝试使用上述片段的挑战的情况。)
也许某些棘手的方法,例如
.split('searchValue')。join('repenterValue')
或一些托管良好的功能给出相同的结果,但肯定的性能比<<代码>本机替换()/polyfill替换()
/repleent() + regexp
polyfill分配的其他方法
幼稚,但支持较旧的浏览器 (最好避免)
例如,我们也可以通过不使用 object.defineproperty()使用我的旧幼稚分配方法:
它应该很好地用于IE7+上的基本用途。
但 AS 在这里 @sebastian-simon解释了,这可以在更多情况下造成次要问题高级用途。例如:
完全值得信赖,但
实际上很重,我建议的选择有点乐观。就像我们信任环境一样(浏览器和 node.js ) -2021。另外,它是标准/著名,因此不需要任何特殊考虑。
但是,甚至可能会有一些较旧的浏览器或一些意外的问题,而多填充仍然可以支持和解决更多可能的环境问题。因此,如果我们需要可能的最大支持,我们可以使用 polyfill库 like:
https:// polyfill.io/
专门用于替换:
Of course in 2021 the right answer is:
String.prototype.replaceAll()
If you don't want to deal with replace() + RegExp.
But what if the browser is from before 2020?
In this case we need polyfill (forcing older browsers to support new features) (I think for a few years will be necessary).
I could not find a completely right method in answers. So I suggest this function that will be defined as a polyfill.
My suggested options for
replaceAll
polyfill:replaceAll
polyfill (with global-flag error) (more principled version)replaceAll
polyfill (With handling global-flag missing by itself) (my first preference) - Why?Minified (my first preference):
Try it:
Browser support:
The result is the same as the native replaceAll in case of the first argument input is:
null
,undefined
,Object
,Function
,Date
, ... ,RegExp
,Number
,String
, ...Ref: 22.1.3.19 String.prototype.replaceAll ( searchValue, replaceValue)
+ RegExp Syntax
Important note: As some professionals mention it, many of recursive functions that suggested in answers, will return the wrong result. (Try them with the challenged case of the above snippet.)
Maybe some tricky methods like
.split('searchValue').join('replaceValue')
or some well managed functions give same result, but definitely with much lower performance thannative replaceAll()
/polyfill replaceAll()
/replace() + RegExp
Other methods of polyfill assignment
Naive, but supports even older browsers (be better to avoid)
For example, we can support IE7+ too, by not using Object.defineProperty() and using my old naive assignment method:
And it should work well for basic uses on IE7+.
But as here @sebastian-simon explained about, that can make secondary problems in case of more advanced uses. E.g.:
Fully trustable, but heavy
In fact, my suggested option is a little optimistic. Like we trusted the environment (browser and Node.js), it is definitely for around 2012-2021. Also it is a standard/famous one, so it does not require any special consideration.
But there can be even older browsers or some unexpected problems, and polyfills still can support and solve more possible environment problems. So in case we need the maximum support that is possible, we can use polyfill libraries like:
https://polyfill.io/
Specially for replaceAll:
我喜欢这种方法(看起来更干净):
I like this method (it looks a little cleaner):
截至2020年8月,有一个第4阶段提案 向eCmascript添加
preplaceall
方法string
。现在,它得到了 Chrome 85+,Edge 85+,Firefox 77+,Safari 13.1+的支持。
用法与 方法:
以下是一个示例用法:
它在,但存在多填充:
在 v8 实验标志后面的引擎
- Harmony-string-Replaceall
。在 v8网站上了解更多信息。
As of August 2020 there is a Stage 4 proposal to ECMAScript that adds the
replaceAll
method toString
.It's now supported in Chrome 85+, Edge 85+, Firefox 77+, Safari 13.1+.
The usage is the same as the
replace
method:Here's an example usage:
It's supported in most modern browsers, but there exist polyfills:
It is supported in the V8 engine behind an experimental flag
--harmony-string-replaceall
.Read more on the V8 website.
如果字符串包含类似的模式,例如
abccc
,您可以使用以下方式:If the string contains a similar pattern like
abccc
, you can use this:以前的答案太复杂了。只需使用 这样的功能:
示例:
The previous answers are way too complicated. Just use the replace function like this:
Example:
经过几次试验和大量失败,我发现以下功能在浏览器兼容性和易用性时似乎是最好的全能功能。这是我发现的旧浏览器的唯一工作解决方案。 (是的,即使旧的浏览器灰心并过时,一些旧应用程序仍然大量使用浏览器(例如old visual basic 6 applications或 excel .xlsm宏带有表单。)
无论如何,这就是简单的函数。
After several trials and a lot of fails, I found that the below function seems to be the best all-rounder when it comes to browser compatibility and ease of use. This is the only working solution for older browsers that I found. (Yes, even though old browser are discouraged and outdated, some legacy applications still make heavy use of OLE browsers (such as old Visual Basic 6 applications or Excel .xlsm macros with forms.)
Anyway, here's the simple function.
尽管人们提到了对正则的使用,但是如果您想替换文本,无论文本情况如何,都有更好的方法。像大写或小写。使用以下语法:
您可以参考详细示例。
Although people have mentioned the use of regex, there's a better approach if you want to replace the text irrespective of the case of the text. Like uppercase or lowercase. Use the below syntax:
You can refer to the detailed example here.
如果您试图确保即使在替换之后即使您要寻找的字符串也不存在,则需要使用循环。
例如:
完成后,您仍然会有“测试ABC”!
解决此问题的最简单循环是:
但是,每个周期都会两次运行替换。也许(有被投票的风险)可以组合起来,以稍微有效但可读性较低:
这在寻找重复的字符串时可能特别有用。
例如,如果我们有“ a ,, b”,我们希望删除所有重复的逗号。
[在那种情况下,可以做。重置(/,+/g,','),但是在某个时候,正则是复杂的,足够慢到足以循环。]
If you are trying to ensure that the string you are looking for won't exist even after the replacement, you need to use a loop.
For example:
When complete, you will still have 'test abc'!
The simplest loop to solve this would be:
But that runs the replacement twice for each cycle. Perhaps (at risk of being voted down) that can be combined for a slightly more efficient but less readable form:
This can be particularly useful when looking for duplicate strings.
For example, if we have 'a,,,b' and we wish to remove all duplicate commas.
[In that case, one could do .replace(/,+/g,','), but at some point the regex gets complex and slow enough to loop instead.]
我的实施,非常自我解释
My implementation, very self explanatory
您可以简单地使用以下方法
You can simply use below method
以下功能对我有用:
现在调用这样的函数:
只需将此代码复制并粘贴到浏览器控制台中进行测试即可。
The following function works for me:
Now call the functions like this:
Simply copy and paste this code in your browser console to TEST.
我使用拆分和加入或此功能:
I use split and join or this function:
现在有一个完成的建议用于集成
string.string.prototype.replacealty.replaceall 进入官方规范。最终,开发人员不必为
替换
提出自己的实现 - 而是现代的JavaScript引擎将在本地支持它。该提案在第4阶段,,意思是 一切都已完成,所有剩下的都用于浏览器开始实施它。
它
以下是实施详细信息:
您可以看到一个规格符合的 polyfill 在这里。
在受支持的环境中,以下片段将记录
foo-bar-baz
,而不会丢弃错误:There is now a finished proposal for integrating
String.prototype.replaceAll
into the official specification. Eventually, developers will not have to come up with their own implementations forreplaceAll
- instead, modern JavaScript engines will support it natively.The proposal is at stage 4, which means that everything is complete, and all that's left is for browsers to start implementing it.
It has shipped in the latest versions of Chrome, Firefox, and Safari.
Here are the implementation details:
You can see a specification-compliant polyfill here.
In supported environments, the following snippet will log
foo-bar-baz
, without throwing an error:如果使用库是您的选择,那么您将获得带有库功能的测试和社区支持的好处。例如, string.js 库具有一个替换()函数,可实现您要寻找的内容:
If using a library is an option for you then you will get the benefits of the testing and community support that goes with a library function. For example, the string.js library has a replaceAll() function that does what you're looking for:
在我的应用程序中,我使用一个为此目的最强大的自定义功能,甚至在更简单的情况下包装
split/join
解决方案,在Chrome 60和Firefox 54中,它更快一点( jsben.ch )比其他解决方案。我的计算机运行Windows 7 64位。优点是,此自定义功能可以同时使用字符串或字符同时处理许多替换,这对于某些应用程序可能是捷径。
像上述 split/join 解决方案一样,下面的解决方案没有任何逃生字符的问题,其方式与正则表达方法不同。
文档如下:
公平地说,我运行了基准测试没有参数测试。
这是我的测试集,使用node.js:
和结果:
In my applications, I use a custom function that is the most powerful for this purpose, and even wrapping the
split/join
solution in the simpler case, it is a little bit faster in Chrome 60 and Firefox 54 (JSBEN.CH) than other solutions. My computer runs Windows 7 64 bits.The advantage is that this custom function can handle many substitutions at the same time using strings or characters, which can be a shortcut for some applications.
Like the above split/join solution, the solution below doesn't have any problems with escape characters, differently than the regular expression approach.
The documentation is below:
To be fair, I ran the benchmark with no parameter test.
Here is my test set, using Node.js:
And the results:
在2019年11月,将新功能添加到JavaScript,
string.prototype.replaceall()
。目前,它仅支持在此处阅读。
In November 2019, a new feature is added to the JavaScript,
string.prototype.replaceAll()
.Currently it's only supported with Babel, but maybe in the future it can be implemented in all the browsers. For more information, read here.