Array Syntax series: Array.from ()

Array.from()You can create an array object in the following ways:

• Pseudo-Array object ( length any object that has a property and several indexed properties)
• Can iterate over objects (can get elements in objects, such as map and Set, etc.)

Array.from()Method has an optional parameter mapFn that allows you to execute the method again on the last generated array map before returning. Which means  Array.from(obj, mapFn, thisArg)  it's equivalent Array.from(obj).map(mapFn, thisArg);

example Array from a Stringarray.from (' Foo '); //["F", "O", "O"] Array from a Setlet S=NewSet ([' foo ', window]); Array.from (s); //["foo", Window] Array from a Maplet M=NewMap ([[1, 2], [2, 4], [4, 8]]); Array.from (m); //[ [1, 2], [2, 4], [4, 8]]Array from an Array-like object (arguments)functionf () {returnarray.from (arguments);} F (1, 2, 3);//[1, 2, 3]Using arrow functions and Array.from//Using a arrow function as the map function to//manipulate the ElementsArray.from ([1, 2, 3], x = x +x); //[2, 4, 6]//Generate A sequence of numbers//Since The array is initialized with ' undefined ' on each position,//The value of ' V ' below would be ' undefined 'Array.from ({length:5}, (V, i) = =i);//[0, 1, 2, 3, 4]

Array Syntax series: Array.from ()