Javascript - 对创建的数组元素执行操作 [英] Javascript - Performing actions on Array elements on creation

问题描述

我试图在Javascript中创建一个对象/类，它的行为像一个数组，但增加了一些功能。

I'm trying to create an Object/Class in Javascript that behaves like an Array but with some added functionalities.

我使用这些简单的线：

var Newclass = Array
Newclass.prototype.get_by_id = function(){}

但是，我试图执行一些操作，当我调用这个新类，因此我添加的元素

However, I'm trying to perform some actions just when I call this new class, so elements I'm adding to this are treated (and transformed, if needed) in a specific way.

我想知道是否有一种方法使它在飞行中，所以我可以做一些事情：

I'm wondering if there is a way of making it on the fly, so I could do something like:

var a = New Newclass('hello', 'goodbye', 'good afternoon')

自动获取变量 a / p>

And automatically, get variable a to be (for example):

console.log(a)
["HELLO", "GOODBYE", "GOOD AFTERNOON"]

我知道如何使用循环和数组函数知道如果有无法覆盖构造函数（在此 Newclass ），因此它会在创建时自动应用于其所有元素，

I know how to do it with loops and Array functions (like map and so), but I'd like to know if there is anyway to overwrite the constructor (on this Newclass) so it gets applied automatically for everyone of its elements on creation, without breaking anything.

感谢大家的时间和答案。但是，我必须说这不是重复，因为我不是问如何使用参数（或如果它们存在），但如何使用它们在构造一个数组派生类，我发现是完全不同的。

Thank you everyone for your time and answers. However, I must say this is not a duplicate, as I'm not asking how to work with arguments (or if they exist), but how to work with them on the construction of an Array derivated class, which I find is totally different.

即使知道参数参数存在，我仍然不知道如何处理这些参数的构造函数 Array ，并且仍然具有此类对象的所有本机函数。

Even knowing the arguments parameter exists, I still don't know how to process these arguments on the constructor of the Array and having still all the native functions of this kind of object.

推荐答案

您可以制作自己的数组派生：

You can make your own derivative of an Array:

function uppercaseStringArray(){
    Array.call(this);
    for(var i = 0; i < arguments.length; i++) this.push(arguments[i]);
}
uppercaseStringArray.prototype = Object.create(Array.prototype);
uppercaseStringArray.prototype.push = function(string){
    Array.prototype.push.call(this, string.toUpperCase());
}

这个工作原理与你期望的一样，它仍然具有正常数组的所有属性：

This works exactly like you expect and it still has all the properties normal arrays have:

function uppercaseStringArray(){
    Array.call(this);
    for(var i = 0; i < arguments.length; i++) this.push(arguments[i]);
}
uppercaseStringArray.prototype = Object.create(Array.prototype);
uppercaseStringArray.prototype.push = function(string){
    Array.prototype.push.call(this, string.toUpperCase());
}

var a  = new uppercaseStringArray('tomato', 'apple', 'pear');

console.log(a);

document.write('[' + a.join(', ') + ']');

您可以修改push方法以获取无限量的参数。但请注意，这是不一个完整的数组， a [5] ='thingy'将不修改数组的长度，所以一定要使用只有方法来添加和删除你的数组。

You could modify the push method to take an unlimited amount of arguments. Please note, however, that this is not a full array, as a[5] = 'thingy' will not modify the length of your array, so be sure to use only methods to add and remove from your array.

这也标识为 Array 和 uppercaseStringArray 使用 instanceof 。您可以向数组中添加自己的方法，例如您的 get_by_id 函数。

This also indentifies itself as both an Array and an uppercaseStringArray using instanceof. And you can add your own methods to the array, like your get_by_id function in its prototype.

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