function(){} vs new Function() vs eval(function(){}) (v8)

Revision 8 of this benchmark created by Richard van Velzen on

Description

https://developer.mozilla.org/en/JavaScript/Reference/Functions_and_function_scope says

Functions defined by function expressions and function declarations are parsed only once, while those defined by the Function constructor are not. That is, the function body string passed to the Function constructor must be parsed every time it is evaluated. Although a function expression creates a closure every time, the function body is not reparsed, so function expressions are still faster than "new Function(...)". Therefore the Function constructor should be avoided whenever possible.

Which sounds bad.

Preparation HTML

<script>
 function fNormal()            {for(var i=0,a=0; i<1000; i++) {a += 1;}}
      var fStatic = function() {for(var i=0,a=0; i<1000; i++) {a += 1;}},
          fCtor = new Function('for(var i=0,a=0; i<1000; i++) {a += 1};');
eval('var fEval = function()   {for(var i=0,a=0; i<1000; i++) {a += 1}};');
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Function expression
fStatic();
ready
Function constructor
fCtor();
ready
A function created with eval()
fEval();
ready
A function created the "normal" way
fNormal();
ready

Revisions

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