以下是我的解决方案:

例如，我假设我们有一个包含三个值对的对象:

function findKey(object, value) {

    for (let key in object)
        if (object[key] === value) return key;

    return "key is not found";
}

const object = { id_1: "apple", id_2: "pear", id_3: "peach" };

console.log(findKey(object, "pear"));
//expected output: id_2

我们可以简单地编写一个findKey(数组，value)，它接受两个参数，一个是对象，一个是你正在寻找的键的值。因此，该方法是可重用的，您不需要每次都手动迭代对象，只需为该函数传递两个参数。

如果你有一个数组值的对象。这里有一个很好的例子。让我们假设您希望根据所拥有的文件的扩展名显示一个图标。具有相同图标的所有扩展都在相同的对象值下。

注意:将这里的case包装在一个对象中要比使用大量case进行切换要好。

检查下面的代码片段(用es6编写)，看看我们如何为特定的扩展返回特定的键。

我从这个git仓库拿到了扩展名列表

// Oject that contains different icons for different extentions const icons = { "music": ["mp3", "m4a", "ogg", "acc", "flac","m3u", "wav"], "video": ["mp4","webm", "mkv", "avi", "mov", "m4v", "mpeg"], "image": ["jpg", "gif", "png", "jpeg", "tif", "psd", "raw", "ico"], "archives": ["zip", "rar", "tar", "dmg", "jar"], "3d-files": ["3ds", "dwg", "obj", "dae", "skp", "fbx"], "text": ["doc", "rtf", "txt", "odt", "tex"], "vector-graphics":["ai", "svg"], "pdf": ["pdf"], "data": ["xml", "csv", "xls"] } const get_icon_Key =( icons_object,file_extention) => { // For each key we chack if the value is contained in the list of values let key = Object.keys(icons_object).find( k=> icons[k].find( // At this leve we check if the extention exist in the array of the specific object value ie. 'music', 'video' ... icons_ext => icons_ext === file_extention) // if we find it means this is the key we are looking for ? true: false); return key } console.log(`The icon of for mp3 extention is: => ${get_icon_Key(icons,"mp3")}`) console.log(`The icon of for mp4 extention is: => ${get_icon_Key(icons,"mp4")}`)

我使用这个函数:

Object.prototype.getKey = function(value){
  for(var key in this){
    if(this[key] == value){
      return key;
    }
  }
  return null;
};

用法:

// ISO 639: 2-letter codes
var languageCodes = {
  DA: 'Danish',
  DE: 'German',
  DZ: 'Bhutani',
  EL: 'Greek',
  EN: 'English',
  EO: 'Esperanto',
  ES: 'Spanish'
};

var key = languageCodes.getKey('Greek');
console.log(key); // EL

function getKeyByValue(object, value) {
  return Object.keys(object).find(key => object[key] === value);
}

ES6，没有原型突变或外部库。

的例子,

函数getKeyByValue(对象，值){ 返回种(对象)。Find (key =>对象[key] === value); ｝ Const map = {"first": "1"， "second": "2"}; console.log (getKeyByValue(地图,“2”));

http://jsfiddle.net/rTazZ/2/

var a = new Array(); 
    a.push({"1": "apple", "2": "banana"}); 
    a.push({"3": "coconut", "4": "mango"});

    GetIndexByValue(a, "coconut");

    function GetIndexByValue(arrayName, value) {  
    var keyName = "";
    var index = -1;
    for (var i = 0; i < arrayName.length; i++) { 
       var obj = arrayName[i]; 
            for (var key in obj) {          
                if (obj[key] == value) { 
                    keyName = key; 
                    index = i;
                } 
            } 
        }
        //console.log(index); 
        return index;
    } 

function extractKeyValue(obj, value) {
    return Object.keys(obj)[Object.values(obj).indexOf(value)];
}

用于闭包编译器提取编译后未知的键名

更性感的版本，但使用未来对象。项功能

function objectKeyByValue (obj, val) {
  return Object.entries(obj).find(i => i[1] === val);
}