javascript test if it is an array

Array.isArray(variableName)

Array.isArray(object);

// If you want to test if a variable (object) is an instance of 
// an array. You can use the Array.isArray(varName) method
// this method takes one argument, the variable or object you want to test
// and returns true, if the argument is an array 
// or false, if the argument is not an array

if (Array.isArray(object)) {
	// is true
} else {
	// is false
}

Array.isArray([1, 2, 3, 4]); // Returns true
Array.isArray(4); // returns false
// this could be used for flattening an array of arrays

if(Array.isArray(myVarToTest)) {
	// myVatToTest is an array
} else {
	// myVarToTest is not an array
}