BarelyBlogging

On the Yahoo! user interface blog I just saw their post “with Statement Considered Harmful“. Good advice.

Here are a few more things that I never do in JavaScript:

1. Never use the “with” statement (as described above)
2. Never use single line “//” comments. Use “/**/”. One day your code is going to be mangled and the newlines removed (perhaps by a crappy content management system), and suddenly your code will be commented out.

   Before:

   // a comment
   alert('ping!');

   After: (UH OH!)

   // a comment alert('ping!');

3. Never omit the semi-colon after a statement. Again, this is to protect your code in case the newlines are removed, and to make the code easier to parse (by humans and machines).

   Before:

   var t = 'ping!'
   alert('ping!')

   After: (ERROR)

   var t = 'ping!' alert('ping!')

   This can be harder than it seems! For example, in the following example you should add a semi-colon after the closing brace:

   var myFunc =
   function() {
   alert('ping!');
   }

4. Never omit the optional brackets { } around a statement. This can prevent some hard-to-debug errors when you add and remove code.

   Before: (MISLEADING INDENT!)

   if (true)
       alert('ping!');
       deleteItem();

   Fixed: (UNAMBIGUOUS)

   if (true) {
       alert('ping!');
   }
   deleteItem();

To check your code for missing semicolons and brackets, use JSLint.

This entry was posted on Tuesday, April 11th, 2006 at 3:11 pm and is filed under JavaScript, programming. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.