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JavaScript JavaScript Foundations Strings Methods: Part 1

Robert Chamblee
Robert Chamblee
12,711 Points
Posted by Robert Chamblee
Robert Chamblee
12,711 Points

Semicolon Neglect.

I notice sometimes in these videos that a semicolon is not added at the end of a line and yet Chrome still executes it without giving an error. Is it just a Chrome thing to forgive that lack of semicolon or is it typical of all browsers? At what point would that become an issue and break your program?

2 Answers

notf0und
notf0und
11,940 Points

I believe JavaScript has Automatic Semicolon Insertion (ASI for short) that acts on JS code. In JavaScript, there are certain things that require semi-colons, and certain things that don't. Here's a blog post that helps to fully understand what's going on: http://inimino.org/~inimino/blog/javascript_semicolons

Here's another: http://bclary.com/2004/11/07/#a-7.9.1

Aaron Graham
Aaron Graham
18,033 Points
Aaron Graham
Aaron Graham
18,033 Points

This lays it out pretty well: http://stackoverflow.com/questions/2846283/what-are-the-rules-for-javascripts-automatic-semicolon-insertion-asi In short, in certain places you can omit them and they will be automatically inserted when your code is interpreted.