Why Doesn't My JavaScript `replace()` Method Change My String?

Understanding the replace() Method in Strings

In programming, the replace() method allows you to replace a specific substring with another in a given string. Recently, a user encountered an issue when attempting to replace smart quotes and registered symbols with their regular counterparts.

The user employed the following code:

str.replace(/[“”]/g, '"');
str.replace(/[‘’]/g, "'");

However, this code failed to produce the desired result. This is because, in JavaScript, strings are immutable. The replace() method generates a new string, leaving the original one unchanged.

Solution:

To correctly replace the smart quotes and symbols, the code should be modified as follows:

str = str.replace(/[“”]/g, '"');
str = str.replace(/[‘’]/g, "'");

Alternatively, a single statement can achieve the same outcome:

str = str.replace(/[“”]/g, '"').replace(/[‘’]/g,"'");

By assigning the new string back to the original variable, you effectively overwrite the original string with the modified one.

Additional Notes:

It is important to note that the code assumes UTF-16 encoding for characters. If your strings contain characters outside the Basic Multilingual Plane (which includes smart quotes and registered symbols), you may need to specify the unicode flag (u) to ensure correct matching.

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