[英]efficient way to search an associative, multi-dimensional array (object) using JavaScript and/or jQuery for key based on value
I have an object that looks similar to this: 我有一个看起来像这样的对象:
var arr = {};
arr.planes = { prop1 : 'a', prop2 : 'b', prop3 : 'c' };
arr.trains = { prop1 : 'x', prop2 : 'y', prop3 : 'z' };
arr.autos = { prop1 : 'red', prop2 : 'orange', prop3 : 'blue' };
I am trying to write a function (that is fast and efficient) that will return the key (or array of keys if there are more than 1) of the outer-most array based on a key/value pair nested within. 我正在尝试编写一个函数(快速而有效),它将返回基于嵌套在其中的键/值对的最外层数组的键(或键数组,如果有多于1个)。 Something like:
就像是:
function getKey(obj, prop, val) {
// do some stuff...
return key;
}
var myKey = getKey(arr, 'prop2', 'orange');
The value of myKey should be "autos". myKey的值应该是“autos”。
I'm pretty sure this can be done with a couple of nested for loops but these arrays are rather large and I'm thinking that, especially using jquery's grep(), there has to be a better way... or maybe not - I'm just stumped at the moment. 我很确定这可以通过几个嵌套的for循环完成,但是这些数组相当大,我在想,特别是使用jquery的grep(),必须有更好的方法......或者可能不是 - 我此刻难倒。
Any insight would be greatly appreciated!! 任何见解都将非常感谢!!
Other than changing your data structure like chris suggests this is pretty much your only option: 除了更改像chris这样的数据结构外,这几乎是你唯一的选择:
function getKey(obj, prop, val) {
var keys = [];
for (var key in obj) {
if (obj[key].hasOwnProperty(prop) && obj[key][prop] === val) {
keys.push(key);
}
}
return keys;
}
Nested loops are not required and you only go over each array element once.. pretty efficient in my opinion. 嵌套循环不是必需的,你只需要遍历每个数组元素..在我看来非常有效。
You might be surprised how fast a for loop can execute over an array in modern browsers. 您可能会惊讶于for循环在现代浏览器中对阵列执行的速度有多快。
But, you can also maintain different data structures for this. 但是,您也可以为此维护不同的数据结构。
Just use some loops to build a new object structured like so 只需使用一些循环来构建一个像这样结构化的新对象
var map = {
prop1: {a: ["planes"], x: ["trains"], red: ["autos"]}
, prop2: {...}
};
function getKey(prop, val) {
return map[prop][val] || [];
}
then lookups are extremely fast from that point on. 从那时起,查找速度非常快。
I assume the values are scalar, otherwise this wont work because only scalars can be used as property names. 我假设值是标量,否则这不会起作用,因为只有标量可以用作属性名称。
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