根据值获取对象键

Question

I have a use case where I have an object of varying values, and I need to get all of these keys that have a specific value. For instance, here is a sample object:

myObject = {
    Person1: true,
    Person2: false,
    Person3: true,
    Person4: false
};

The key names will vary, but the valid values are true or false. I want to get an array of the names that have a value of true:

myArray2 = [
    'Person1',
    'Person3
];

I've been trying to use various lodash functions in combination such as _.key() and _.filter, but with no luck. How can I accomplish this? I'm open to pure JS or Lodash options.

UPDATE: I accepted mhodges' answer below as the accepted answer, although others gave me the same answer. Based on that, I came up with a Lodash version:

var myArray = _(myObject).keys().filter(function(e) {
    return myObject[e] === true;
}).value();

Answer 1

If I understand your question correctly, you should be able to use basic .filter() for this.

myObject = {
    Person1: true,
    Person2: false,
    Person3: true,
    Person4: false
};

var validKeys = Object.keys(myObject).filter(function (key) { 
    return myObject[key] === true; 
});

Answer 2

Use Object.keys():

var object = {
    1: 'a',
    2: 'b',
    3: 'c'
};
console.log(Object.keys(object));

Alternative solution:

var keys = [];
for (var key in object) {
    if (object.hasOwnProperty(key)) {
        keys.push(key);
    }        
}    
console.log(keys);

Don't forget to check a key with the help of hasOwnProperty() , otherwise this approach may result in unwanted keys showing up in the result.

Answer 3

You can do this with Object.keys() and filter() .

 var myObject = { Person1: true, Person2: false, Person3: true, Person4: false }; var result = Object.keys(myObject).filter(function(e) { return myObject[e] === true; }) console.log(result) 

ES6 version with arrow function

var result = Object.keys(myObject).filter(e => myObject[e] === true)

Answer 4

Since Lodash was tagged: With pickBy the values can be filtered (and the keys obtained with _.keys ):

var myArray2  = _.keys(_.pickBy(myObject));

 var myObject = { Person1: true, Person2: false, Person3: true, Person4: false }; var myArray2 = _.keys(_.pickBy(myObject)); console.log(myArray2 ); 

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