Regex to replace first occurence of match in javascript

Question

I have below test cases as input:

[This is my test] [This is my test] My name is xyz.

Want Expected output as :
[This is my test] My name is xyz.
.
[This is my test] My name is xyz.
Want Expected output as:
My name is xyz.

For above test cases I want to replace only first occurrence of '[This is my test] ' with blank. I don't want to replace second occurrence of match.

How do I resolve this using regex in JavaScript?

Thanks in advance.

ETA:

I just want to give more clarification that, i dont want to use hard coded value in regex , i want to use variable in regex.
Assume that [This is my test] is stored in one variable i.e. var defaultMsg = "[This is my test] ";

Do you really need a regexp? If the string you are looking for is known, just read this: stackoverflow.com/questions/3244817/… — mplungjan
– mplungjan, Commented Jul 15, 2010 at 8:24

mplungjan · Accepted Answer · 2013-03-10 18:01:14Z

6

Anyone try this?

<script>
var defaultMsg ="[This is my test]"
var str         = "[This is my test] [This is my test] My name is xyz.";
str=str.replace(defaultMsg,"");
alert(str);
</script>

No need for regexp and replace does not care about special chars if the source string is not a regular expression object but just a string. Tested Mozilla 1.7, FF3.6.6, Safari 5, Opera 10 and IE8 windows XP sp3. Not sure I understand why this was voted down if it does the job with a minimum of fuss.

to replace all occurrences, add a g (note: this is not standard):

str=str.replace(defaultMsg,"","g"); // "gi" for case insensitivity

replace MDN

edited Mar 10, 2013 at 18:01

answered Jul 14, 2010 at 9:39

mplungjan

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1 Comment

mplungjan Over a year ago

"improper" ? wow. downvoted for being improper posting code that works.

Brock Adams · Accepted Answer · 2010-07-14 09:57:55Z

3

If the search pattern is in a string variable and can contain special characters, then it must be escaped. Like so:

var defaultMsg  = "[This is my test] ";

//-- Must escape special characters to use in a RegEx.
defaultMsg      = defaultMsg.replace (/([\!\$\(\)\*\+\.\/\:\=\?\[\\\]\^\{\|\}])/g, "\\$1")

var zRegEx      = new RegExp (defaultMsg, '');

var Str         = '[This is my test] [This is my test] My name is xyz.';

Str             = Str.replace(zRegEx, "");

console.log (Str);  //-- Or use alert()

answered Jul 14, 2010 at 9:57

Brock Adams

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3 Comments

mplungjan Over a year ago

Nope. defaultMsg='[This is my test]'; '[This is my test] [This is my test] My name is xyz.'.replace(defaultMsg,""); works too.

Brock Adams Over a year ago

@mplungjan: Did you test your approach on the top 5 browsers and for different combinations of special characters? Check it against the ECMAScript spec? What happens if the programmer needs to use match(), test() or exec() instead? The only way that works in all cases is to properly escape the string.

mplungjan Over a year ago

But that is a different discussion. We are not talking match, test or exec, just replace the first occurrence of some string from another string. can be does with indexOf and length, but replace using a string works. Tested now you insist on Mozilla 1.7, FF3.6.6, Safari 5, Opera 10 and IE8 - granted it is on windows XP sp3, but I rest my case

cletus · Accepted Answer · 2010-07-14 09:27:28Z

0

Sure. Use replace():

var s = "[This is my test] [This is my test] My name is xyz.";
alert(s.replace(/\[This is my test\] /, ''));

If you want to replace all occurrences:

alert(s.replace(/\[This is my test\] /g, ''));

answered Jul 14, 2010 at 9:27

cletus

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2 Comments

pravin Over a year ago

Thanks folks, I just want to give more clarification that, i dont want to use hard coded value in regex , i want to use variable in regex. Assume that [This is my test] is stored in one variable i.e. var defaultMsg = "[This is my test] ";

Dominic K Over a year ago

Then just call it on defaultMsg: alert(defaultMsg.replace(/\[This is my test\] /g, ''));

Thariama · Accepted Answer · 2010-07-14 09:28:41Z

0

This will do what you want:

str= '[This is my test] [This is my test] My name is xyz.';

str = str.replace(/\[This is my test\]/,"");

To replace all occurences of '[This is my test]' you need to call:

str = str.replace(/\[This is my test\]/g,"");

answered Jul 14, 2010 at 9:28

Thariama

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1 Comment

pravin Over a year ago

Thanks folks, I just want to give more clarification that, i dont want to use hard coded value in regex , i want to use variable in regex. Assume that [This is my test] is stored in one variable i.e. var defaultMsg = "[This is my test] ";

LukeH · Accepted Answer · 2010-07-14 09:31:59Z

0

The JavaScript replace function defaults to non-global so it only replaces the first match:

var foo = '[This is my test] [This is my test] My name is xyz.';
var bar = foo.replace(/\[This is my test\]\s/, '');

If you wanted to replace all occurrences of the string then make the regex global by appending a g:

var bar = foo.replace(/\[This is my test\]\s/g, '');

edited Jul 14, 2010 at 9:31

answered Jul 14, 2010 at 9:26

LukeH

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1 Comment

pravin Over a year ago

Thanks folks, I just want to give more clarification that, i dont want to use hard coded value in regex , i want to use variable in regex. Assume that [This is my test] is stored in one variable i.e. var defaultMsg = "[This is my test] ";

klox · Accepted Answer · 2010-07-14 09:45:01Z

0

var str="[This is my test] [This is my test] My name is xyz.?";
var patt1=(/[[This is my test]].*My name is xyz/i);
document.write(str.match(patt1));

answered Jul 14, 2010 at 9:45

klox

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Comments

Gabriele Petrioli · Accepted Answer · 2010-07-14 09:45:50Z

0

var originalText = '[This is my test] [This is my test] My name is xyz.';
var defaultMsg = "[This is my test] ";

alert( originalText.replace( defaultMsg , '' ) );

answered Jul 14, 2010 at 9:45

Gabriele Petrioli

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Comments

Toto · Accepted Answer · 2010-07-14 09:56:21Z

0

This will do the trick:

var foo = '[This is my test] ';// or whatever you want
foo = foo.replace(/([\[\]])/, '\\$1', 'g'); // add all special chars you want
var patern = new RegExp(foo);
var myString = '[This is my test] [This is my test] My name is xyz.';
var result = myString.replace(patern, '');

edited Jul 14, 2010 at 9:56

answered Jul 14, 2010 at 9:45

Toto

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