javascript check if array key exists code example

Example 1: javascript does key exist

var person={"name":"Billy","age":20}
person.hasOwnProperty("name"); // true
person.hasOwnProperty("sex"); // false

Example 2: javascript hashtable contains key

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

Example 3: javascript method to see if item exists in array

var fruits = ["Apple", "Banana", "Mango", "Orange", "Papaya"];
    
    // Check if a value exists in the fruits array
    if(fruits.indexOf("Mango") !== -1){
        alert("Value exists!")
    } else{
        alert("Value does not exists!")
    }

Example 4: check if a key exists in an object javascript

"key" in obj // true, regardless of the actual value