CODEWITHSUNDEEP
javascriptvariablesloops
kamaci
kamaci

Reputation: 75137

What are the differences of that iterations?

What are the differences of that iterations:

var recordId;
for(recordId in deleteIds){
  ...
}

and 

for(var recordId in deleteIds){
  ...
}

It says implicit definition(what is it), is there a performance difference between them?

Upvotes: 2

Views: 50

Answers (2)

Rickard
Rickard

Reputation: 2335

the two samples are equivalent, however the first may come from following a recommended pattern in JavaScript which is declaring all variables at the top of every function.

Sample:

var recordId,
    i = 0;

for(recordId in deleteIds){
  ...
  i++;
}

More explanation on this can be found here JSLint error: Move all 'var' declarations to the top of the function

Upvotes: 1

Matt
Matt

Reputation: 75317

An "implicit declaration" is a variable that is assigned a value before it is declared using a var. The scenario leaves the variable declared in the largest possible scope (the "global" scope).

However, in both your code examples, recordId is declared before it is assigned (var recordId), so there's no problem.

As to your other question, no, there is no noticeable performance difference.

Upvotes: 1

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