// Treated as:

// a = b + c(d + e).foo();

with the suggestion that the preceding statement be terminated with a

semicolon.

Some suggest instead the use of leading semicolons on lines starting

with '(' or '[', so the line is not accidentally joined with the

previous one. This is known as a defensive semicolon, and is

particularly recommended, because code may otherwise become ambiguous

when it is rearranged. For example:

a = b + c

;(d + e).foo()

// Treated as:

// a = b + c;

// (d + e).foo();

Initial semicolons are also sometimes used at the start of JavaScript

libraries, in case they are appended to another library that omits a

trailing semicolon, as this can result in ambiguity of the initial

statement.

The five restricted productions are return, throw, break, continue, and

post-increment/decrement. In all cases, inserting semicolons does not

fix the problem, but makes the parsed syntax clear, making the error

easier to detect. return and throw take an optional value, while break

and continue take an optional label. In all cases, the advice is to keep

the value or label on the same line as the statement. This most often

shows up in the return statement, where one might return a large object

literal, which might be accidentally placed starting on a new line. For

post-increment/decrement, there is potential ambiguity with

pre-increment/decrement, and again it is recommended to simply keep

these on the same line.

return

a + b;

// Returns undefined. Treated as:

// return;

// a + b;

// Should be written as:

// return a + b;

Comment syntax is the same as in C++, Swift and other programming

languages.

Single-line comments begin with // and continue until the end of the

line. A second type of comments can also be made; these start with /*

and end with */ and can be used for multi-line comments.

A third type of comment, the hashbang comment, starts with #! and