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I have the following JavaScript object:

var obj = {
    "key1" : val,
    "key2" : val,
    "key3" : val
}

Is there a way to check if a key exists in the array, similar to this?

testArray = jQuery.inArray("key1", obj);

does not work.

Do I have to iterate through the obj like this?

jQuery.each(obj, function(key,val)){}

I have the following JavaScript object:

var obj = {
    "key1" : val,
    "key2" : val,
    "key3" : val
}

Is there a way to check if a key exists in the array, similar to this?

testArray = jQuery.inArray("key1", obj);

does not work.

Do I have to iterate through the obj like this?

jQuery.each(obj, function(key,val)){}

• javascript
• jquery

Share Improve this question Follow edited Jun 23, 2015 at 19:37 Sumner Evans 9,14755 gold badges3131 silver badges4848 bronze badges asked Jun 15, 2013 at 18:09 user2065483user2065483 1,22533 gold badges99 silver badges1212 bronze badges 6

• 4 js - object literal :) (not jQuery object) – funerr Commented Jun 15, 2013 at 18:10
• True ;), shows that I don't have a js background - started with the jQuery library right from the start, and I believe I need to learn the basics... – user2065483 Commented Jun 15, 2013 at 18:30
• obj.has("key1") will work if you are using ES6. – Diablo Commented May 30, 2017 at 9:03
• 2 Possible duplicate of Checking if a key exists in a JavaScript object? – Gerhard Powell Commented Sep 15, 2017 at 21:56
• 2 @Diablo I think you're trying to say obj.hasOwnProperty("key1") instead of just has? – Aminu Kano Commented Aug 21, 2018 at 9:11

 |  Show 1 more comment

10 Answers 10

Sorted by: Reset to default 205

Use the in operator:

testArray = 'key1' in obj;

---

Sidenote: What you got there, is actually no jQuery object, but just a plain JavaScript Object.

That's not a jQuery object, it's just an object.

You can use the hasOwnProperty method to check for a key:

if (obj.hasOwnProperty("key1")) {
  ...
}

var obj = {
    "key1" : "k1",
    "key2" : "k2",
    "key3" : "k3"
};

if ("key1" in obj)
    console.log("has key1 in obj");

=========================================================================

To access a child key of another key

var obj = {
    "key1": "k1",
    "key2": "k2",
    "key3": "k3",
    "key4": {
        "keyF": "kf"
    }
};

if ("keyF" in obj.key4)
    console.log("has keyF in obj");

Above answers are good. But this is good too and useful.

!obj['your_key']  // if 'your_key' not in obj the result --> true

It's good for short style of code special in if statements:

if (!obj['your_key']){
    // if 'your_key' not exist in obj
    console.log('key not in obj');
} else {
    // if 'your_key' exist in obj
    console.log('key exist in obj');
}

Note: If your key be equal to null or "" your "if" statement will be wrong.

obj = {'a': '', 'b': null, 'd': 'value'}
!obj['a']    // result ---> true
!obj['b']    // result ---> true
!obj['c']    // result ---> true
!obj['d']    // result ---> false

So, best way for checking if a key exists in a obj is:'a' in obj

use the hasOwnProperty(),

if (!obj.hasOwnProperty(key)) {

}

For Example :

const object1 = {
        one : 'value of one',
        two : 'value of two',
        three : 'value of three',
    };

console.log(object1.hasOwnProperty('one'));
// expected output: true

console.log(object1.hasOwnProperty('value of one'));
// expected output: false

console.log(object1.hasOwnProperty('four'));
// expected output: false

You can try this:

const data = {
  name : "Test",
  value: 12
}

if("name" in data){
  //Found
}
else {
  //Not found
}

map.has(key) is the latest ECMAScript 2015 way of checking the existance of a key in a map. Refer to this for complete details.

the simplest way is

const obj = {
  a: 'value of a',
  b: 'value of b',
  c: 'value of c'
};

if(obj.a){
  console.log(obj.a);
}else{
  console.log('obj.a does not exist');
}

You can use Object.keys(object).indexOf() scenario:

1. With Object.keys(object) you create an array of keys.
2. Use indexOf() to find out if the key you're looking for is part of this array:

let testObject = {
a: 1,
b: 2
}

Object.keys(testObject).indexOf('a') > -1 // expect true - the key exists
Object.keys(testObject).indexOf('c') > -1 // expect false - the key didn't exists

This works for me like a charm. I'm inside a foreach function this didn't work obj.hasOwnProperty("key1") also this "key1" in obj

let $schedule = {lesson:'asd',age:'sad'}
    
$schedules.forEach(function(e) {
    if (e['lesson']) {
        $title = e.lesson.lesson_name;
    } else {
        $title = 'No lesson Attached';
    }
});

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