Javascript Performance: Assign object fields at creation or later?

Question

Does anyone know whether there are any performance trade-offs/advantages to assigning an object's fields at creation rather than later e.g.

var exObj = new exampleObject(name, date);

OR

var exObj = new exampleObject();

exObj.name = "blah"; exObj.date = "blah";

(assuming you've created your class accordingly)

Also, as a side thought, given that JS arrays are stored as objects, am I correct in assuming that there are no performance differences between using one over the other ? (For some reason using an array with a numeric index "feels" faster.)

Cheers

N

jasssonpet · Accepted Answer · 2011-01-17 13:03:21Z

1

Test it yourself - http://jsperf.com/assign-object-fields-at-creation-or-later

answered Jan 17, 2011 at 13:03

jasssonpet

2,11915 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

nick-brown Over a year ago

Many thanks for this - I actually had planned to test it myself if there were no responses but I hadn't used/been aware of jsperf.com before so this simplifies things considerably. For those who are interested, the latter method is fractionally quicker (at least on FF 3.6.13).

Collectives™ on Stack Overflow

Javascript Performance: Assign object fields at creation or later?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related