Library in JavaScript has a FUNCTION with a leading semicolon:

Let us see the different uses of including a leading semicolon:

• Concatenate

The purpose to include semicolon is to safely concatenate several JS files into one.

• Preceding Code

A leading semicolon protects from preceding code, which may have been improperly closed. A semicolon prevents this from occurring. If this is the case, then adding a semicolon will fix it.

• Appending

The leading semicolon in immediately-invoked function expressions PREVENT errors when appending the file during CONCATENATION. This concat is to a file containing an expression improperly concluded with a semicolon

Let’s see an example. Let’s SAY we are concatenating two files with self-invoking functions:

• Function ONE

• Function TWO

• Now concatenating it will give the following result:

• Function TWO can have a leading semicolon:

• Now after concatenation, you can see the semi-colon is VISIBLE:

This helps in preventing any kind of errors when appending the file during concatenation.