How to check if a value exists in an object using JavaScript

Question

I have an object in JavaScript:

var obj = {
   "a": "test1",
   "b": "test2"
}

How do I check that te

Answer 1

You can use the Array method .some:

var exists = Object.keys(obj).some(function(k) {
    return obj[k] === "test1";
});

Answer 2

if( myObj.hasOwnProperty('key') && myObj['key'] === value ){
    ...
}

Answer 3

Use a for...in loop:

for (let k in obj) {
    if (obj[k] === "test1") {
        return true;
    }
}

Answer 4

Shortest ES6+ one liner:

let exists = Object.values(obj).includes("test1");

Answer 5

Try:

var obj = {
   "a": "test1",
   "b": "test2"
};

Object.keys(obj).forEach(function(key) {
  if (obj[key] == 'test1') {
    alert('exists');
  }
});

Or

var obj = {
   "a": "test1",
   "b": "test2"
};

var found = Object.keys(obj).filter(function(key) {
  return obj[key] === 'test1';
});

if (found.length) {
   alert('exists');
}

This will not work for NaN and -0 for those values. You can use (instead of ===) what is new in ECMAScript 6:

 Object.is(obj[key], value);

With modern browsers you can also use:

var obj = {
   "a": "test1",
   "b": "test2"
};

if (Object.values(obj).includes('test1')) {
  alert('exists');
}

Answer 6

For a one-liner, I would say:

exist = Object.values(obj).includes("test1");
console.log(exist);