How to check if key exists in array of object

Question

I am trying to find out if the given key exists in array of object. if the value key exists then i want to return true else false.

i giving input of key from text box and then checking if the key exists in array of objects, but i couldn't get it.

here is what i have tried

code:

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}]

var val = $("input[name='type_ahead_input']").val();

if (obj[val]) {
    console.log('exists');
} else {
    console.log('does not exist');
}

if i give input as 'the carribean' which exists in array of object, even then its outputting in console as does not exist.

how can i resolve this?

Answer 1

you can use typeof to check if key exist

if (typeof obj[0][val] !== "undefined" ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

Note: There is index 0 coz the object that you are checking is an element 0 of the array obj

---

Here is a fiddle:

var obj = [{
		"7364234":"hsjd",
		"tom and jerry":"dsjdas",
		"mickey mouse":"kfjskdsad",
		"popeye the sailor man":"alkdsajd",
		"the carribean":"kasjdsjad"
	}];

	if ( typeof obj[0]["the carribean"] !== 'undefined' ) {
		console.log('exists');
	} else {
		console.log('does not exist');
	}

---

As suggested by Cristy below, you can also use obj[0][val] === undefined

You can also:

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}];

var val = "7364234";

if ( val in obj[0] ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

Answer 2

I suggest using Array.some() to know if a key exists and Array.find() to get the value of the found key, together with some recent syntax:

let arr = [{"foo": 1}, {"bar":2}];

function isKeyInArray(array, key) { 
  return array.some(obj => obj.hasOwnProperty(key)); 
}

function getValueFromKeyInArray(array, key) { 
  return array.find(obj => obj[key])?.[key]; 
}

console.log(isKeyInArray(arr, "foo"), isKeyInArray(arr, "bar"), isKeyInArray(arr, "baz"));
console.log(getValueFromKeyInArray(arr, "foo"), getValueFromKeyInArray(arr, "bar"), getValueFromKeyInArray(arr, "baz"));