javascript javascript查找数组项的父项
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javascript find parent of array item
提问by Mark
I have an array item like this:
我有一个这样的数组项：
var array = USA.NY[2];
// gives "Albany"
{"USA" : {
"NY" : ["New York City", "Long Island", "Albany"]
}}
I want to find the state from just having the array. How do I do this? Thanks.
我想从只有数组中找到状态。我该怎么做呢？谢谢。
function findParent(array) {
// do something
// return NY
}
回答by Martijn
In Javascript, array elements have no reference to the array(s) containing them.
在 Javascript 中，数组元素没有对包含它们的数组的引用。
To achieve this, you will have to have a reference to the 'root' array, which will depend on your data model.
Assuming USA is accessible, and contains only arrays, you could do this:
为此，您必须引用“根”数组，这取决于您的数据模型。
假设 USA 是可访问的，并且只包含数组，你可以这样做：
function findParent(item) {
var member, i, array;
for (member in USA) {
if (USA.hasOwnProperty(member) && typeof USA[member] === 'object' && USA[member] instanceof Array) {
array = USA[member];
for(i = 0; i < array.length; i += 1) {
if (array[i] === item) {
return array;
}
}
}
}
}
Note that I've renamed the arrayparameter to itemsince you're passing along a value (and array item), and you expect the array to be returned.
If you want to know the nameof the array, you should return memberinstead.
请注意，我已将array参数重命名为，item因为您正在传递一个值（和数组项），并且您希望返回该数组。
如果你想知道数组的名称，你应该返回member。
回答by Frederic Fortier
Here is a generic function that can be used to find the parent key of any kind of multi-dimentional object. I use underscore.js by habit and for conciseness to abstract array vs associative array loops.
这是一个通用函数，可用于查找任何类型的多维对象的父键。我习惯使用 underscore.js 并且为了简洁抽象数组与关联数组循环。
(function (root, struct) {
var parent = null;
var check = function (root, struct) {
_.each(root, function (value, key) {
if (value == struct) {
parent = key;
} else if (root == struct) {
parent = '_root';
} else if (typeof value === 'object') {
check(value, struct);
}
});
}
check(root, struct);
return parent;
})
