javascript 在数组中查找对象而不是循环的更好方法？
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Better way to find object in array instead of looping?
提问by Ron van der Heijden
Example
例子
Link: http://jsfiddle.net/ewBGt/
链接：http: //jsfiddle.net/ewBGt/
var test = [{
"name": "John Doo"
}, {
"name": "Foo Bar"
}]
var find = 'John Doo'
console.log(test.indexOf(find)) // output: -1
console.log(test[find]) // output: undefined
$.each(test, function(index, object) {
if(test[index].name === find)
console.log(test[index]) // problem: this way is slow
})
Problem
问题
In the above example I have an array with objects. I need to find the object that has name = 'John Doo'
在上面的例子中，我有一个包含对象的数组。我需要找到具有name = 'John Doo'
My .eachloop is working, but this part will be executed 100 times and test will contain lot more objects. So I think this way will be slow.
我的.each循环正在运行，但这部分将被执行 100 次并且测试将包含更多的对象。所以我认为这种方式会很慢。
The indexOf()won't work because I cannot search for the name in object.
该indexOf()不会工作，因为我不能搜索的对象名称。
Question
问题
How can I search for the object with name = 'John Doo'in my current array?
如何name = 'John Doo'在当前数组中搜索对象？
回答by Matti Simperi
I have done sometimes "searchable map-object" in this kind of situation. If the array itself is static, you can transform in to a map, where array values can be keys and map values indexes. I assume values to be unique as in your example.
在这种情况下，我有时会做“可搜索的地图对象”。如果数组本身是静态的，您可以转换为映射，其中数组值可以是键和映射值索引。我假设值在您的示例中是唯一的。
Lo-Dash (www.lodash.com) has create selection of utils for easily looping etc. Check it out!
Lo-Dash (www.lodash.com) 已经创建了用于轻松循环等的实用程序选择。看看吧！
Note:But often you really don't have to worry about looping trough array with 100 elements.
注意：但通常你真的不必担心循环包含 100 个元素的槽数组。
回答by Luca Fagioli
jQuery $.grep(or other filtering function) is not the optimal solution.
jQuery $.grep（或其他过滤功能）不是最佳解决方案。
The $.grepfunction will loop through allthe elements of the array, even if the searched object has been already found during the loop.
该$.grep函数将遍历数组的所有元素，即使在循环过程中已找到搜索对象。
From jQuery grep documentation :
来自 jQuery grep 文档：
The $.grep() method removes items from an array as necessary so that all remaining items pass a provided test. The test is a function that is passed an array item and the index of the item within the array. Only if the test returns true will the item be in the result array.
$.grep() 方法根据需要从数组中删除项目，以便所有剩余的项目通过提供的测试。测试是一个函数，它传递一个数组项和数组中该项的索引。只有当测试返回 true 时，该项目才会出现在结果数组中。
Provided that your array is not sorted, nothing can beat this:
如果您的数组未排序，则没有什么比这更好的了：
var getObjectByName = function(name, array) {
// (!) Cache the array length in a variable
for (var i = 0, len = test.length; i < len; i++) {
if (test[i].name === name)
return test[i]; // Return as soon as the object is found
}
return null; // The searched object was not found
}
回答by tomekwi
If you just want to find out if the value is there, you can use lodash's includesfunction like this:
如果你只是想知道这个值是否存在，你可以includes像这样使用 lodash 的函数：
var find = 'John Doo'
[{ "name": "John Doo" }, { "name": "Foo Bar" }].some(function (hash) {
if (_.includes(hash, find)) return true;
});
Documentation:
文档：
回答by sbeliv01
Perhaps you should use the $.grepfunctionality in jQuery:
也许您应该使用$.grepjQuery 中的功能：
var test = [{
"name": "John Doo"
}, {
"name": "Foo Bar"
}]
var find = 'John Doo'
var found = $.grep(test, function(obj){
return obj['name'] == find;
});
console.log(found);
Fiddle: http://jsfiddle.net/ewBGt/3/
回答by CBroe
The only thing you can possibly do is use build-in array methods (if available) in preference over doing the looping yourself – the filtermethod would be applicable here.
您唯一能做的就是使用内置数组方法（如果可用）而不是自己进行循环——该filter方法在这里适用。
But I expect that JS libraries like jQuery used by sbeliv01 in his answer already check for that internally (and provide a fallback solution if these array methods are not available natively) – so don't expect a massive performance boost.
但我希望 sbeliv01 在他的回答中使用的 jQuery 等 JS 库已经在内部检查了它（如果这些数组方法在本机不可用，则提供后备解决方案）——所以不要指望巨大的性能提升。
