NaN. The trick to remove these from an array is to use the filter method and filter the array by Boolean.
var arr = [2, "Anand", "", false, 15, 0, NaN, null, undefined]; //To filter false values just apply filter by Boolean arr.filter(Boolean); //Output would be -- [2. "Anand", 15]
The other way to do this is to write a function that checks if each of the array element is a falsy one and filter it. Like the one below.