var army= ["Marcos", "DeltaForce", "Seals", "SWAT", "HeadHunters"];  

if(army.indexOf("Marcos") !== -1)  {  

  console.log("Yes, the value exists!")  

}else{  

  console.log("No, the value is absent.")  

}  

myArray = Array(/*element1, element2, etc...*/);

​

// If the array 'myArray' contains the element 'valueWeSearch'

if(myArray.includes(valueWeSearch))

{

    // Do something

}

if (typeof array != "undefined" && array != null && array.length != null && array.length > 0) {

    // array exists and is not empty

}

myArr?.[index]

typeof array != "undefined"

    && array != null

    && array.length != null

    && array.length > 0

564

  564

  231