Mastering JavaScript

Before you judge the validity of these arguments, you need to understand what is
affected by ASI. The following statements are affected by ASI:
• An empty statement
• A var statement
• An expression statement
• A do-while statement
• A continue statement
• A break statement
• A return statement
• A throw statement
Chapter 1
The idea behind ASI is to make semicolons optional at the end of a line. This way,
ASI helps the parser to determine when a statement ends. Normally, it ends with a
semicolon. ASI dictates that a statement also ends in the following cases:
• A line terminator (for example, a newline) is followed by an illegal token
• A closing brace is encountered
• The end of the file has been reached
Let's see the following example:
if (a < 1) a = 1 console.log(a)
The console token is illegal after 1 and triggers ASI as follows:
if (a < 1) a = 1; console.log(a);
In the following code, the statement inside the braces is not terminated by a
semicolon:
function add(a,b) { return a+b }
ASI creates a syntactically correct version of the preceding code:
function add(a,b) { return a+b; }
[ 31 ]
www.it-ebooks.info