nl_tokens: In ES6 this trap is called for all operations that require a list of an object s properties including Object . getOwnPropertyNames and Object . keys .
pl_tokens: function ( ) { var trap = this . getTrap ( "ownKeys" ) ; if ( trap === undefined ) { // default forwarding behavior return Reflect . ownKeys ( this . target ) ; } var trapResult = trap . call ( this . <mask> , this . target ) ; if ( trapResult === null || typeof trapResult !== "object" ) { throw new TypeError ( "ownKeys should return an iterator object, got " + trapResult ) ; } return trapResult ; }