Declaring Multiple Variables in JavaScript

Question

Hello,

In JavaScript, it is possible to declare multiple variables like this:

var variable1 = "Hello World!";
var variable2 = "Testing...";
var variable3 = 42;

...or like this:

var variable1 = "Hello World!",
    variable2 = "Testing...",
    variable3 = 42;

Is one method better/faster than the other?

Thanks,

Steve

Answer 1

It's just a matter of personal preference. There is no difference between these two ways, other than a few bytes saved with the second form if you strip out the white space.

Answer 2

var variable1 = "Hello World!";
var variable2 = "Testing...";
var variable3 = 42;

is more readable than:

var variable1 = "Hello World!",
    variable2 = "Testing...",
    variable3 = 42;

But they do the same thing.

Answer 3

The first way is easier to maintain. Each declaration is a single statement on a single line, so you can easily add, remove, and reorder the declarations.

With the second way, it is annoying to remove the first or last declaration because they contain the var keyword and semicolon. And every time you add a new declaration, you have to change the semicolon in the old line to a comma.

Answer 4

It's common to use one var statement per scope for organization. The way all "scopes" follow a similar pattern making the code more readable. Additionally, the engine "hoists" them all to the top anyway. So keeping your declarations together mimics what will actually happen more closely.