Why does console tell me that .filter is not a function? [closed]

Answer 1

Because you're invoking the execution of "filter" on str, which is an object without a function called "filter" of its own nor by prototype. Since filter is not present the property's value is undefined, which cannot be invoked because its type is not function.

Answer 2

The String object does not have a filter method and String is immutable. So in effect str.split('') does not change the value of the string but returns a new String which you are not capturing in a variable.

Try,

console.log(str.split('').filter(fil));

Answer 3

Because filter is an array function (Array.prototype.filter), while you are calling it on a string. str.split returns an array and doesn't change anything to your str. call it like console.log(str.split('').filter(fil)) and it should be fine.