Test case details

Preparation Code

var obj = {}, i = 10000, val;         while ( i-- )         obj[i] = i;

Test cases

Test #1

Object.keys(obj).forEach(function(obj){     val = obj; });

Test #2

for ( var key in obj )     if ( obj.hasOwnProperty(key) )         val = obj[key];

Test #3

var keys = Object.keys(obj), i = 0; l = keys.length; for ( i ; i < l; i++  )     val = obj[i];