如何通过 JavaScript 中的属性获取对象的索引？
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How to get index of object by its property in JavaScript?
提问by rsboarder
For example, I have:
例如，我有：
var Data = [
{ id_list: 1, name: 'Nick', token: '312312' },
{ id_list: 2, name: 'John', token: '123123' },
]
Then, I want to sort/reversethis object by name, for example. And then I want to get something like this:
然后，例如，我想通过对这个对象进行排序/反转name。然后我想得到这样的东西：
var Data = [
{ id_list: 2, name: 'John', token: '123123' },
{ id_list: 1, name: 'Nick', token: '312312' },
]
And now I want to know the index of the object with property name='John'to get the value of the property token.
现在我想知道具有属性的对象的索引name='John'以获取属性令牌的值。
How do I solve the problem?
我该如何解决问题？
采纳答案by Chris Pickett
As the other answers suggest, looping through the array is probably the best way. But I would put it in it's own function, and make it a little more abstract:
正如其他答案所暗示的那样，遍历数组可能是最好的方法。但我会把它放在它自己的函数中，并使它更抽象一点：
function findWithAttr(array, attr, value) {
for(var i = 0; i < array.length; i += 1) {
if(array[i][attr] === value) {
return i;
}
}
return -1;
}
var Data = [
{id_list: 2, name: 'John', token: '123123'},
{id_list: 1, name: 'Nick', token: '312312'}
];
With this, not only can you find which one contains 'John' but you can find which contains the token '312312':
有了这个，您不仅可以找到包含“John”的内容，还可以找到包含标记“312312”的内容：
findWithAttr(Data, 'name', 'John'); // returns 0
findWithAttr(Data, 'token', '312312'); // returns 1
findWithAttr(Data, 'id_list', '10'); // returns -1
EDIT:Updated function to return -1 when not found so it follows the same construct as Array.prototype.indexOf()
编辑：更新函数以在未找到时返回 -1，因此它遵循与Array.prototype.indexOf()相同的构造
回答by German Attanasio
Since the sort part is already answered. I'm just going to propose another elegant way to get the indexOf of a property in your array
由于排序部分已经回答。我只是要提出另一种优雅的方法来获取数组中属性的 indexOf
Your example is:
你的例子是：
var Data = [
{id_list:1, name:'Nick',token:'312312'},
{id_list:2,name:'John',token:'123123'}
]
You can do:
你可以做：
var index = Data.map(function(e) { return e.name; }).indexOf('Nick');
Array.prototype.mapis not available on IE7 or IE8. ES5 Compatibility
Array.prototype.map在 IE7 或 IE8 上不可用。ES5 兼容性
And here it is with ES6 and arrow syntax, which is even simpler:
这里是 ES6 和箭头语法，更简单：
const index = Data.map(e => e.name).indexOf('Nick');
回答by silverlight513
回答by edank
var index = Data.findIndex(item => item.name == "John")
Which is a simplified version of:
这是以下的简化版本：
var index = Data.findIndex(function(item){ return item.name == "John"})
From mozilla.org:
The findIndex() method returns the index of the first element in the array that satisfies the provided testing function. Otherwise -1 is returned.
findIndex() 方法返回数组中满足提供的测试函数的第一个元素的索引。否则返回-1。
回答by Alain T.
If you're having issues with IE, you could use the map() function which is supported from 9.0 onward:
如果您在使用 IE 时遇到问题，您可以使用 9.0 以后支持的 map() 函数：
var index = Data.map(item => item.name).indexOf("Nick");
回答by Andrew D.
Only way known for me is to looping through all array:
我知道的唯一方法是循环遍历所有数组：
var index=-1;
for(var i=0;i<Data.length;i++)
if(Data[i].name==="John"){index=i;break;}
or case insensitive:
或不区分大小写：
var index=-1;
for(var i=0;i<Data.length;i++)
if(Data[i].name.toLowerCase()==="john"){index=i;break;}
On result variable indexcontain index of object or -1 if not found.
结果变量索引包含对象的索引，如果未找到，则为 -1。
回答by Patrik Wallin
a prototypical way
一种典型的方式
(function(){
if (!Array.prototype.indexOfPropertyValue){
Array.prototype.indexOfPropertyValue = function(prop,value){
for (var index = 0; index < this.length; index++){
if (this[index][prop]){
if (this[index][prop] == value){
return index;
}
}
}
return -1;
}
}
})();
// usage:
var Data = [
{id_list:1, name:'Nick',token:'312312'},{id_list:2,name:'John',token:'123123'}];
Data.indexOfPropertyValue('name','John'); // returns 1 (index of array);
Data.indexOfPropertyValue('name','Invalid name') // returns -1 (no result);
var indexOfArray = Data.indexOfPropertyValue('name','John');
Data[indexOfArray] // returns desired object.
回答by Patrik Wallin
Why don't you use a small work-around?
你为什么不使用一个小的解决方法？
Create a new array with names as indexes. after that all searches will use indexes. So, only one loop. After that you don't need to loop through all elements!
创建一个以名称为索引的新数组。之后所有搜索都将使用索引。所以，只有一个循环。之后你不需要遍历所有元素！
var Data = [
{id_list:1, name:'Nick',token:'312312'},{id_list:2,name:'John',token:'123123'}
]
var searchArr = []
Data.forEach(function(one){
searchArr[one.name]=one;
})
console.log(searchArr['Nick'])
http://jsbin.com/xibala/1/edit
http://jsbin.com/xibala/1/edit
live example.
活生生的例子。
回答by Ed Shee
Extended Chris Pickett's answer because in my case I needed to search deeper than one attribute level:
扩展了 Chris Pickett 的答案，因为在我的情况下，我需要搜索比一个属性级别更深的内容：
function findWithAttr(array, attr, value) {
if (attr.indexOf('.') >= 0) {
var split = attr.split('.');
var attr1 = split[0];
var attr2 = split[1];
for(var i = 0; i < array.length; i += 1) {
if(array[i][attr1][attr2] === value) {
return i;
}
}
} else {
for(var i = 0; i < array.length; i += 1) {
if(array[i][attr] === value) {
return i;
}
}
};
};
You can pass 'attr1.attr2' into the function
您可以将 'attr1.attr2' 传递给函数
回答by Ed Shee
You can use Array.sort using a custom function as parameter to define your sorting mecanism.
您可以使用 Array.sort 使用自定义函数作为参数来定义您的排序机制。
In your example, it would give :
在你的例子中，它会给出：
var Data = [
{id_list:1, name:'Nick',token:'312312'},{id_list:2,name:'John',token:'123123'}
]
Data.sort(function(a, b){
return a.name < b.name ? -1 : a.name > b.name ? 1 : 0;
});
alert("First name is : " + Data[0].name); // alerts 'John'
alert("Second name is : " + Data[1].name); // alerts 'Nick'
The sort function must return either -1 if a should come before b, 1 if a should come after b and 0 if both are equal. It's up to you to define the right logic in your sorting function to sort the array.
如果 a 应该在 b 之前，则排序函数必须返回 -1，如果 a 应该在 b 之后，则返回 1，如果两者相等，则返回 0。您可以在排序函数中定义正确的逻辑来对数组进行排序。
Edit : Missed the last part of your question where you want to know the index. You would have to loop through the array to find that as others have said.
编辑：错过了您想知道索引的问题的最后一部分。您必须遍历数组才能找到其他人所说的那样。
