A common question is: How do I know if a variable is an array?
The problem is that the JavaScript operator typeof returns "object":
var fruits = ["Banana", "Orange", "Apple", "Mango"];
typeof fruits; // returns object
typeof fruits; // returns object
The typeof operator returns object because a JavaScript array is an object.
Solution 1:
To solve this problem ECMAScript 5 defines a new method Array.isArray():
Array.isArray(fruits); // returns true
The problem with this solution is that ECMAScript 5 is not supported in older browsers.
Solution 2:
To solve this problem you can create your own isArray() function:
function isArray(x) {
return x.constructor.toString().indexOf("Array") > -1;
}
return x.constructor.toString().indexOf("Array") > -1;
}
The function above always returns true if the argument is an array.
Or more precisely: it returns true if the object prototype contains the word "Array".
Solution 3:
The instanceof operator returns true if an object is created by a given constructor:
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits instanceof Array; // returns true
fruits instanceof Array; // returns true
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