allfn

Summary

Returns a function that returns true if all predicates have passed when applied to its arguments.

Description

Takes one or more predicates and returns a function that takes any number of arguments and returns true if each predicate has returned logical true when applied to these arguments.

Examples

Make sure that both x and y are numbers and produce the correct answer when added up.

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const is_num = x => typeof x == 'number';
const can_answer =
 allfn( (x, y) => is_num(x) && is_num(y) // (1)
 , (x, y) => x + y === 42); // (2)
can_answer( 40, 2); //=> true (3)
can_answer( 20, 30); //=> false (4)
can_answer('40', 2); //=> false (5)

1. 1st predicate: checks both arguments are numbers.

2. 2nd predicate: checks numbers add up to 42.

3. passed: both arguments are numbers and add up to 42.

4. failed: both arguments are numbers but do not add up to 42.

5. failed: 1st argument is not a number.

Parameters

Name	Type	Description
fn	function	One or more predicates

Return

function