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javascriptregexreplacepattern-matchingregexp-replace

RegExp replace do not replaces with pattern

I want to replace #### by ##-## (# := any digit symbol).

if (/^([0-9]{2})([0-9]{2})$/.test(str)) {       
    str = str.replace("/^([0-9]{2})([0-9]{2})$/", "$1-$2");
    console.log(str);
}

In console I get #### (not ##-##).
What I'm doing wrong?

Solution

  • You need to pass a regex to the replace function not a string - in your case you are trying to replace the string literal /^([0-9]{2})([0-9]{2})$/

    str = str.replace(/^([0-9]{2})([0-9]{2})$/, "$1-$2");


    var str = '4455';
snippet.log('before: ' + str);
str = str.replace(/^([0-9]{2})([0-9]{2})$/, "$1-$2");
snippet.log('after: ' + str);
    <!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>