How to check if a key exists in an object in javascript [duplicate]

Question

This question already has answers here:

Checking if a key exists in a JavaScript object? (33 answers)

Closed 9 years ago.

I have the following object literal:

{ 
 'key1': 
 { 
 id: 'rr323',
 d: undefined,
 x: 560,
 y: 150 
 },
 'key2': 
 { 
 id: 'rr231',
 d: undefined,
 x: 860,
 y: 90 
 } 
}

I want to implement an if statement such as below:

if(key DOES NOT exist in object){ 
//perform certain function 
}

I tried the following:

var key = key1;
if(!(key in global_move_obj)){
 // function
}

But that always returns true value when it should return false.

• zzzzBov: var key = key1 in your code should be var key = 'key1', otherwise you're going to check if undefined in global_move_obj.

Answer 1

Use the hasOwnProperty call:

if (!obj.hasOwnProperty(key)) {
}

Answer 2

You can do it like:

var key = 'key1';
if (!('key1' in obj)) {
 ....
} 
// or
if (!(key in obj)) {
}