javascript Array.of和Array.from

Posted 2021-05-03

// Array.of will take all passed arguments and turn into an array

Array.of('One', 2, 'Three', 4);
// ['One', 2, 'Three', 4]

// Array.from will take anything array-like / iterable and it into an array

Array.from({ length: 4 });
// [undefined, undefined, undefined, undefined]

// Array.from also accepts map functions
Array.from({ length: 4 }, x => 'Hello');
// [Hello, Hello, Hello, Hello]

const animals = new Set();

animals.add('Dog');
animals.add('Cat');
animals.add('Hamster');

animals
// Set(3) {"Dog", "Cat", "Hamster"}

Array.from(animals);
// ["Dog, "Cat", "Hamster"]