Question

Option1 : multiple var without assignment

function MyFunction() {

  var a = null;
  var b = null;
  ....
  var z = null;

  a = SomeValue;
  b = SomeValue2;
  ....
}

Option 2: one var statement, no assignment

function MyFunction() {

  var a, b ..., z;

  a = SomeValue;
  b = SomeValue2;
  ....
}

Option 3: multiple var statements with assignment

function MyFunction() {

  var a = SomeValue;
  var b = SomeValue2;
  ....
  var z = SomeValue26;
}

Is there any performance benefit of using a particular option? Is it true for both primitive type assignments AND object reference assignments?

Thanks for your input.

Answer 1

“premature optimization is the root of
all evil”

I don’t think there will be any significant performance change with any of this options.
(IMO) The third option is the most readable option and closest to dynamic memory allocation like C# etc’. But this is my humble opinion, Choose what you like the most.

If it really bothers you and you can’t sleep without an answer, test it with jsPerf.

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@Chad made a jsPerf so you can sleep well tonight…