I have a variable:

var str = "@devtest11 @devtest1";

I use this way to replace @devtest1 with another string:

str.replace(new RegExp('@devtest1', 'g'), "aaaa")

However, its result (aaaa1 aaaa) is not what I expect. The expected result is: @devtest11 aaaa. I just want to replace the whole word @devtest1.

How can I do that?

I have a variable:

var str = "@devtest11 @devtest1";

I use this way to replace @devtest1 with another string:

str.replace(new RegExp('@devtest1', 'g'), "aaaa")

However, its result (aaaa1 aaaa) is not what I expect. The expected result is: @devtest11 aaaa. I just want to replace the whole word @devtest1.

How can I do that?

• javascript
• regex

3 Answers 3

Use the \b zero-width word-boundary assertion.

var str = "@devtest11 @devtest1";
str.replace(/@devtest1\b/g, "aaaa");
// => @devtest11 aaaa

If you need to also prevent matching the cases like hello@devtest1, you can do this:

var str = "@devtest1 @devtest11 @devtest1 hello@devtest1";
str.replace(/( |^)@devtest1\b/g, "$1aaaa");
// => @devtest11 aaaa

Use word boundary \b for limiting the search to words.

Because @ is special character, you need to match it outside of the word.

\b assert position at a word boundary (^\w|\w$|\W\w|\w\W), since \b does not include special characters.

var str = "@devtest11 @devtest1";
str = str.replace(/@devtest1\b/g, "aaaa");

document.write(str);

If your string always starts with @ and you don't want other characters to match

var str = "@devtest11 @devtest1";
str = str.replace(/(\s*)@devtest1\b/g, "$1aaaa");
//                 ^^^^^                ^^

document.write(str);

\b won't work properly if the words are surrounded by non space characters..I suggest the below method

var output=str.replace('(\s|^)@devtest1(?=\s|$)','$1aaaa');