// Array.from () // Array.of () usage
// Array.from () usage
// 1.Array from () array will be a class or an object, it is converted into a real array. The class must have an array length property
. 1 var List = { 2 0: "Han" , . 3 1: "Bai" , . 4 2: "Another" , . 5 3: "Zhao" , . 6 length:. 4 . 7 } . 8 var ARR = Array.from (List) . 9 the console.log (ARR); // output: [ "Han", "Bai", "Liang", "Zhao"]
// can convert 2.Array.from () in the form of a string array
1 var str = 'chenbin' 2 var arr1 = Array.from(str) 3 console.log(arr1);// 输出结果: ["c", "h", "e", "n", "b", "i", "n"]
// 3.Array.from () can be passed a second parameter, map (similar to the array) method (Array.from (obj, mapFn, thisArg) format corresponds Array.from (obj) .map (mapFn , thisArg)), each processing element, the processing element of the array back
1 var arr3 = [1,2,3,4,5] 2 var newarr = new Set(arr3) 3 console.log(Array.from(newarr,item=>item+1));//输出结果: [2, 3, 4, 5, 6]
// Array.of()
// Create a new array variable number of parameters, regardless of the type and number of parameters
Difference // Array.of () constructor and Array: an integer that the processing parameters
// Array (7) represents create an empty array of length 7
// Array.of (7) represents the creation of an array which has an array of individual elements 7, its length is 1
. 1 var of arr1 the Array = (10 ) 2 the console.log (of arr1); // [empty × 10] is a length of array 10 is empty . 3 var arr2 is = Array.of (10 ) . 4 the console.log (arr2 is); / / [10] is an array with a single element 10, its length is 1 . 5