5 ms·
The comma first pattern is pretty common. I've seen it used in JavaScript (as well as JSON), SQL and Haskell; I'm sure there are others. Some encourage this so
by Xophmeister 12y ago
The comma first pattern is pretty common. I've seen it used in JavaScript (as well as JSON), SQL and Haskell; I'm sure there are others.
Some encourage this so you can comment out a line without having to add/remove commas. However, this isn't the case if you want to comment out the first line; so in effect, it just moves the problem from the bottom to the top of the list. Other proponents say it's easier to spot typos (i.e., missing commas). For example:
var something = {
foo: 'bar',
abc: '123'
quux: null,
xyz: 456
};
vs:
var something = {
foo: 'bar'
, abc: '123'
quux: null
, xyz: 456
};
In the second one, it's clearer that there's a comma missing.
Personally, I think it's ugly and, while I'm sure I've erroneously omitted commas before, they're caught by the parser. No example comes immediately to mind where missing a comma can be interpreted as something other than a parse error.