7 Predicate Functions for Cleaning an Array

isNumber, Number.isInteger, Array.isArray, isDefined, hasProp and more

A predicate is a function that returns a boolean.

This article looks at several predicate functions that can be used together with the filter array method to clean up an array.

The filter method creates a new array containing all elements that pass the test implemented by the given predicate function.

The isNumber function takes a value and returns true if is a number otherwise returns false. It detects numbers using the typeof operator.

Consider the following array.

We can use isNumber predicate together with the filter method and create a new array holding only numbers.

The built-in Number.isInteger detects if the given value is an integer.

Here is an example of creating a new array from an existing one containing only integers.

The isTruthy function returns true for truthy values, otherwise, it returns false.

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