如何在javascript数组中按键和值查找对象的索引 [英] How to find index of an object by key and value in an javascript array

问题描述

鉴于：

var peoples = [
  { "attr1": "bob", "attr2": "pizza" },
  { "attr1": "john", "attr2": "sushi" },
  { "attr1": "larry", "attr2": "hummus" }
];

通缉：

对象索引 attr === value 例如 attr1 ===john或 attr2 ===鹰嘴豆泥

更新：
请阅读我的问题仔细，我不想通过$ .inArray找到对象，也不想获取特定对象属性的值。请考虑这个以获得答案。谢谢！

Update: Please, read my question carefully, i do not want to find the object via $.inArray nor i want to get the value of a specific object attribute. Please consider this for your answers. Thanks!

推荐答案

功能方法

所有酷孩子都在行动编程（你好React用户）这些天所以我想我会给出功能性的解决方案。在我看来它实际上比迄今为止提出的和 每个循环的阻碍好很多语法非常优雅。

The Functional Approach

All the cool kids are doing functional programming (hello React users) these days so I thought I would give the functional solution. In my view it's actually a lot nicer than the imperatival for and each loops that have been proposed thus far and with ES6 syntax it is quite elegant.

现在有一种很好的方法可以做到这一点，叫做 findIndex 根据数组元素是否匹配（一如既往，检查浏览器），它接受一个函数返回 true / false 虽然兼容性。

There's now a great way of doing this called findIndex which takes a function that return true/false based on whether the array element matches (as always, check for browser compatibility though).

var index = peoples.findIndex(function(person) {
  return person.attr1 == "john"
}

使用ES6语法，您可以写下：

With ES6 syntax you get to write this:

var index = peoples.findIndex(p => p.attr1 == "john")

---

（旧）功能方法

TL; DR

如果你e寻找 index 其中 peoples [index] .attr1 ==john使用：

var index = peoples.map(function(o) { return o.attr1; }).indexOf("john");

说明

第1步

使用 .map（） 获取给定特定键的值数组：

Use .map() to get an array of values given a particular key:

var values = object_array.map(function(o) { return o.your_key; });

上面的行从这里开始：

var peoples = [
  { "attr1": "bob", "attr2": "pizza" },
  { "attr1": "john", "attr2": "sushi" },
  { "attr1": "larry", "attr2": "hummus" }
];

到这里：

var values = [ "bob", "john", "larry" ];

第2步

现在我们只使用 .indexOf（） 查找我们想要的键的索引（当然，也是我们要查找的对象的索引）：

Now we just use .indexOf() to find the index of the key we want (which is, of course, also the index of the object we're looking for):

var index = values.indexOf(your_value);

解决方案

我们结合以上所有：

var index = peoples.map(function(o) { return o.attr1; }).indexOf("john");

或者，如果您更喜欢ES6语法：

Or, if you prefer ES6 syntax:

var index = peoples.map((o) => o.attr1).indexOf("john");

---

演示：

---

Demo:

var peoples = [
  { "attr1": "bob", "attr2": "pizza" },
  { "attr1": "john", "attr2": "sushi" },
  { "attr1": "larry", "attr2": "hummus" }
];

var index = peoples.map(function(o) { return o.attr1; }).indexOf("john");
console.log("index of 'john': " + index);

var index = peoples.map((o) => o.attr1).indexOf("larry");
console.log("index of 'larry': " + index);

var index = peoples.map(function(o) { return o.attr1; }).indexOf("fred");
console.log("index of 'fred': " + index);

var index = peoples.map((o) => o.attr2).indexOf("pizza");
console.log("index of 'pizza' in 'attr2': " + index);

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