javascript" associative"阵列访问 [英] javascript "associative" array access

问题描述

我有一个简单的模拟aarray有两个元素：

I have a simple simulated aarray with two elements:

bowl["fruit"]="apple";
bowl["nuts"]="brazilian";

我可以通过以下事件访问该值：

I can access the value with an event like this:

onclick="testButton00_('fruit')">with `testButton00_`

function testButton00_(key){
    var t = bowl[key];
    alert("testButton00_: value = "+t);
}

但是每当我尝试使用密钥从代码中访问aarray时只是一个非显式的字符串，我得到了未定义。我是否必须以转义的'key'传递参数。有任何想法吗？ tia。

However whenever I try to access the aarray from within code with a key that is just a non-explicit string I get undefined. Do I have somehow have to pass the parameter with the escaped 'key'. Any ideas? tia.

推荐答案

密钥可以是动态计算的字符串。举一个你传递的不起作用的例子。

The key can be a dynamically computed string. Give an example of something you pass that doesn't work.

鉴于：

var bowl = {}; // empty object

你可以说：

bowl["fruit"] = "apple";

或者：

bowl.fruit = "apple"; // NB. `fruit` is not a string variable here

甚至：

var fruit = "fruit";
bowl[fruit] = "apple"; // now it is a string variable! Note the [ ]

或者如果你真的想要：

bowl["f" + "r" + "u" + "i" + "t"] = "apple";

这些对碗的效果都相同对象。然后你可以使用相应的模式来检索值：

Those all have the same effect on the bowl object. And then you can use the corresponding patterns to retrieve values:

var value = bowl["fruit"];
var value = bowl.fruit; // fruit is a hard-coded property name
var value = bowl[fruit]; // fruit must be a variable containing the string "fruit"
var value = bowl["f" + "r" + "u" + "i" + "t"];

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