function at ( n ) { n = Math . trunc ( n ) || 0 ; if ( n < 0 ) n += this . length ; if ( n < 0 || n >= this . length ) return undefined ; return this [ n ] ; } const TypedArray = Reflect . getPrototypeOf ( Int8Array ) ; for ( const C of [ Array , String , TypedArray ] ) { Object . defineProperty ( C . prototype , 'at' , { value : at , writable : true , enumerable : false , configurable : true } ) ; }