如何获得数组的键在Javascript？

问题描述

我有这个code创建一个数组：

I have an array created with this code:

var widthRange = new Array();
widthRange[46] = { min:0,  max:52 };
widthRange[66] = { min:52, max:70 };
widthRange[90] = { min:70, max:94 };

我想每个值46，66，90在一个循环。我试图为（以widthRange VAR键）但是这给了我额外的属性的一大堆（我以为他们是在对象上的功能）。因为值不连续的，我不能使用常规的循环。

I want to get each of the values 46, 66, 90 in a loop. I tried for (var key in widthRange) but this gives me a whole bunch of extra properties (I assume they are functions on the object). I can't use a regular for loop since the values are not sequential.

推荐答案

您需要调用<$c$c>hasOwnProperty函数来检查是否该属性的对象本身实际上定义（而不是它的原型），像这样的：

You need to call the hasOwnProperty function to check whether the property is actually defined on the object itself (as opposed to its prototype), like this:

for (var key in widthRange) {
    if (key === 'length' || !widthRange.hasOwnProperty(key)) continue;
    var value = widthRange[key];
}

请注意，您需要为长度单独检查。结果
但是，你不应该在这里使用一个数组的全部;你应该使用常规的对象。所有的JavaScript对象作为关联数组。

Note that you need a separate check for length.
However, you shouldn't be using an array here at all; you should use a regular object. All Javascript objects function as associative arrays.

例如：

var widthRange = { };  //Or new Object()
widthRange[46] = { sel:46, min:0,  max:52 };
widthRange[66] = { sel:66, min:52, max:70 };
widthRange[90] = { sel:90, min:70, max:94 };

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