nl_tokens: Creates a new object with the certain keys excluded . This is used instead of delete since that has performance implications in V8 .
pl_tokens: function ( srcObject , excludeKeys ) { var destObject = { } , key ; for ( key in srcObject ) { if ( srcObject . hasOwnProperty ( key ) ) { if ( - 1 === excludeKeys . indexOf ( key ) ) { destObject [ key ] = srcObject [ <mask> ] ; } } } return destObject ; }