Why Does `String.replace()` with a Dollar Sign ($) Result in an Empty String?

String.replace() Oddity with Dollar Sign ($) Replacement

When using string replacement in JavaScript, a peculiar behavior can arise with the dollar sign ($) character. Consider the following code snippet:

<code class="javascript">var text = "as";
text = text.replace(text,"$\'");
console.log(text);</code>

Surprisingly, this code outputs an empty string. Our initial expectation would have been for it to print $'. What explains this unexpected result?

The answer lies in the special significance of $ in JavaScript regular expressions and the string replace method. In this context, $ denotes the end of the string, a special behavior that overrides its typical role as a literal character.

To use $ as an actual character in the replacement string, it is necessary to escape it using $$. By modifying the code as follows, we obtain the intended output:

<code class="javascript">var text = "as";
text = text.replace(text, "$$\'");
console.log(text);</code>

This updated code correctly prints $' to the console, showcasing the proper usage of $ as a literal character in regular expressions.

The above is the detailed content of Why Does `String.replace()` with a Dollar Sign ($) Result in an Empty String?. For more information, please follow other related articles on the PHP Chinese website!