Question

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Difference between using var and not using var in JavaScript
What is the advantage of initializing multiple javascript variables with the same var keyword?

I have the following code:

var row = $link.attr('data-row'),
    a = 2,
    b = a;

Is this exactly the same as:

var row = $link.attr('data-row');
var a = 2;
var b = a;

When I use jslint it keeps suggesting I use just the one var. What do people normally do to make the code most readable. Also is there a way to stop jslint complaining?

Answer 1

There is no practical difference. Use whichever suits you best. You can tell JSLint to allow many var statements by adding the following directive at the top the file:

/*jslint vars: true */

Note that there is no difference in speed between the two variants:

The part of the spec that deals with variable declarations states the following:

For each VariableDeclaration and VariableDeclarationNoIn d in code, in
source text order do

• Let dn be the Identifier in d.
• Let varAlreadyDeclared be the result of calling env’s HasBinding concrete
  method passing dn as the argument.
• If varAlreadyDeclared is false, then
  • Call env’s CreateMutableBinding concrete method passing dn and
    configurableBindings as the arguments.
  • Call env’s SetMutableBinding
    concrete method passing dn, undefined, and strict as the arguments.

There is nothing in there that would differentiate between separate and combined var statements.