How to use from method in es6

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In es6, the from method is used to convert array-like objects and traverable objects into real arrays, and the result is a new array instance that has been converted, with the syntax "Array.from (pseudo-array objects or iterable objects that you want to convert to an array, callback functions, this objects when callback functions are executed)".

This tutorial operating environment: windows10 system, ECMAScript version 6. 0, Dell G3 computer.

How to use from method in es6

This method is used to convert two types of objects into real arrays: array-like objects and traverable objects.

Grammar

Array.from (arrayLike, mapFun, thisArg)

Parameters.

ArrayLike: required. Pseudo-array objects or iterable objects that you want to convert to an array

MapFun: optional. If this parameter is specified, each element in the new array executes the callback function.

ThisArg: optional. The this object when the callback function mapFun is executed.

Return value

A new array instance

Examples are as follows:

Generate an array from String

Array.from ('foo'); / / ["f", "o", "o"]

Generate an array from Set

Const set = new Set (['foo',' bar', 'baz',' foo']); Array.from (set); / / ["foo", "bar", "baz"]

Generate an array from Map

Const map = new Map ([[1, 2], [2, 4], [4, 8]); Array.from (map); / [[1, 2], [2, 4], [4, 8]] const mapper = new Map ([['1','a'], ['2','b']]); Array.from (mapper.values ()); / / ['a','b']; Array.from (mapper.keys ()) / / ['1percent,' 2']

Generate an array from a class array object (arguments)

Function f () {return Array.from (arguments);} f (1, 2, 3); / / [1, 2, 3] is all the content of this article "how to use the from method in es6". Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.