'+' operator has many uses including addition, concatenation, and most importantly type conversion. Generally, we use '+' operator for addition and at some times for concatenation. It also has a lot of use in type conversion. It is very easy to convert a string into a number.
<html> <body> <script> var num = "23"; int = +num; document.write(int); document.write("</br>"); document.write(typeof int); </script> </body> </html>
Not only type-conversion, this operator is also used to convert booleans to numbers. It changes the boolean values such as true or false to 1 and 0 respectively.
<html> <body> <script> document.write(+true); document.write("</br>"); document.write(+false); </script> </body> </html>