ES6 syntax (array extension)

{let arr= Array.of (3, 4, 7, 9, 11); Console.log (' arr ', arr);//[3,4,7,9,11]Let empty =Array.of (); Console.log (empty); //[]}//ES6 adds the FROM function to array to convert other objects into arrays. //of course, other objects are also required and not all, and two objects can be converted to an array. //1. Objects with iterator interfaces are deployed, such as: Set,map,array. //2. Class Array object, what is called the class array object, is an object must have the Length property, no length, the empty array is turned out. {    //Converting ArraysLet P = Document.queryselectorall (' P '); Let PArr=Array.from (P); Parr.foreach (function(item) {Console.log (item.textcontent);//es6, hehe Hey, happy move.    }); //MapConsole.log (Array.from ([1, 3, 5],function(item) {returnItem * 2        })) //2,6,10}//array padding{Console.log (' Fill-7 ', [1, ' A ', Undefined].fill (7))//7,7,7Console.log (' Fll,pos ', [' A ', ' B ', ' C '].fill (' 7 ', 1, 3));//a 7 7 (1,3) represents the starting position, and 7 is the fill content}//Traverse related{    //Take position     for(Let index of[' 1 ', ' C ', ' KS '].keys ()) {Console.log (' Keys ', index);//0 1 2    }    //Take value     for(Let value of[' 1 ', ' C ', ' KS '].values ()) {Console.log (' Values ', value);//1 C KS (There is compatibility problem, need to introduce import ' Babel-polyfill ')    }    //take position and value     for(Let [index, value] of[' 1 ', ' C ', ' KS '].entries ()) {Console.log (' Values ', index, value);//0 1 2,1 C ks    }}//assigns a member to another place within the current array's inner array{Console.log ([1, 2, 3, 4, 5].copywithin (0, 3, 4));//4,2,3,4,5 (Start position 0, starting from the third reading, the cutoff position is 4, i.e. 5 numbers)Console.log ([1, 2, 3, 4, 5].copywithin (1, 3, 4))//1,4,3,4,5Console.log ([1, 2, 3, 4, 5].copywithin (0,-2,-1))//4,2,3,4,5}//Find{Console.log ([1, 2, 3, 4, 5, 6].find (function(item) {returnItem > 3//4 Only find the first value, not the next one.    })); Console.log ([1, 2, 3, 4, 5, 6].findindex (function(item) {returnItem > 3//3 was looking for the subscript.    }));}//NaN{Console.log (' Number ', [1,2,nan].includes (1)];//true if this value is includedConsole.log (' number ', [1,2,nan].includes (NaN));//true}

ES6 syntax (array extension)