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Editor to share with you what is the use of the Array.from () method in ES6. I hope you will get something after reading this article. Let's discuss it together.

Array.from ()

The Array.from method is used to turn two types of objects into real arrays: objects of class arrays (array-like object) and objects that can be traversed (iterable) (including ES6's new data structures Set and Map).

Let arrayLike = {'0forth:' asides, '1clients:' baked, '2percent:' cased, length: 3}; / / ES5 is written as var arr1 = [] .slice.call (arrayLike); / / ['averse,' baked,'c'] / / ES6 is written as let arr2 = Array.from (arrayLike) / / NodeList object let ps = document.querySelectorAll ('p'); Array.from (ps) .forEach (function (p) {console.log (p);}); / / arguments object function foo () {var args = Array.from (arguments) / /...} / / A string is converted into a character array str.split ('') Array.from ('hello') / / [undefined, undefined, undefined] let namesSet = new Set ([' averse,'b']) Array.from (namesSet) / / ['averse,' b'] Array.from ({length: 3}); / / [undefined, undefined, undefined]

For browsers that have not yet deployed this method, you can use the Array.prototype.slice method instead:

Const toArray = () = > Array.from? Array.from: obj = > [] .slice.call (obj) ()

Array.from can also accept the second parameter, which acts like the array's map method to process each element and put the processed value into the returned array.

Array.from (arrayLike, x = > x * x); / equivalent to Array.from (arrayLike) .map (x = > x * x); Array.from ([1je 2jue 3], (x) = > x * x) / / [1,4,9] / / Array.from callback function var arr1 = Array.from ([1m 2m 3], function (item) {return item*item;}) Var arr2 = Array.from ([1jue 2jue 3]) .map (function (item) {return item*item;}); var arr3 = Array.from ([1JI 2je 3], (item) = > item*item); console.log (arr1); / / [1,4,9] console.log (arr2); / / [1,4,9] console.log (arr3); / / [1,4,9]

It is worth reminding that the extension operator (...) can also convert some data structures to arrays.

/ / arguments object function foo () {var args = [... arguments];} / NodeList object [. Document.querySelectorAll ('div')] after reading this article, I believe you have a certain understanding of "what is the use of the Array.from () method in ES6". If you want to know more about it, welcome to follow the industry information channel, thank you for reading!

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