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Chofoteddy
Asked: 2020-01-14 14:10:23 +0800 CST 2020-01-14 14:10:23 +0800 CST

"Array-like objects" What are they; how to identify them?

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I am not an expert in English, but reading about ES6 I have come across on several occasions that they mention Array-like objects (especially when I read about Map , Set , WeakMap , WeakSet ), as in the following context:

Other collections support for-of too

for–ofis not just for arrays. It also works on most array-like objects, like DOM NodeLists.

From what little I understand, it looks something like what jQuery returns when they query a list of elements with (example) $('a').

I understand that an Array is already an object, but what does the term Array-like object refer to ? How do I create one? What is the purpose compared to an array?

javascript

1 Answers

  1. Best Answer

    An array-like object is an object that resembles an array because it represents a set of elements and has a property length, however it does not directly have the very useful methods of , , etc.Array.prototypesortfilter

    A very common example of this type of object is argumentsthat it refers to the arguments that are sent to a function:

    funtion foo(a, b) {
    console.log(arguments[0]);
}

foo(1, 2); // imprime 1

    Since we cannot directly invoke any method, Array.prototypewhat we do is first convert it to an array:

    var args = Array.prototype.slice.call(arguments);

    The method slicehas the ability to work with array-like objects and therefore conversion is possible.

    Other examples are DOM objects obtained through methods like document.getElementsByClassName, known as NodeList. This is an alternative way to convert to array:

    var nodeList = document.getElementsByClassName('.tuClase'),
var nodeArray = [].slice.call(nodeList);

    Ideally you don't have to create this type of objects, it will always be easier to use arrays when you need a collection of elements, this makes it easier to integrate a program into a project, since if all the functions use arrays there is no need to do conversions. You just have to be aware of what they are and how they differ from arrays.

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