How to check if array element exists or not in javascript?

I am working with titanium ,

my code looks like as ,

var currentData = new Array();

if(currentData[index]!==""||currentData[index]!==null||currentData[index]!=='null')
{
    Ti.API.info("is exists  " + currentData[index]);
    return true;
}
else
{   
    return false;
}

I am passing index to array currentData,

For non existing element , i am still not able to detect it using above code

---

Use typeof arrayName[index] === 'undefined'

ie

if(typeof arrayName[index] === 'undefined') {
    // does not exist
}
else {
    // does exist
}

---

var myArray = ["Banana", "Orange", "Apple", "Mango"];

if (myArray.indexOf(searchTerm) === -1) {
  console.log("element doesn't exist");
}
else {
  console.log("element found");
}

---

Consider the array a:

var a ={'name1':1, 'name2':2}

If you want to check if 'name1' exists in a, simply test it with in :

if('name1' in a){
console.log('name1 exists in a')
}else
console.log('name1 is not in a')

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