RxJS Ninja - Numbers

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@rxjs-ninja/rxjs-number provides operators for querying, filtering and modifying number values, and Observable for generating number emitters.

Function and Operator categories

Create

Functions and Operators for creating Observable number values

// Generate a number stream, take `6`, add `1` return the modulus `3` value
fromNumber().pipe(take(6), add(1), mod(3)).subscribe();
// Output: `1, 2, 0, 1, 2, 0`

Distribution

Operators for handling the distribution of numbers, these will return a single value from an Iterable of numbers

const source$ = from([
  [1, 2, 3],
  [10, 15, 8],
  [5, 10, 100],
]);

// Get the Mean
source$.pipe(mean()).subscribe();
// Output: `2, 11, 38.333`

// Get the Median
source$.pipe(median()).subscribe();
// Output: `2, 15, 100`

// Get the Minimum Number
source$.pipe(min()).subscribe();
// Output: `1, 8, 5`

// Get the Minimum Number
source$.pipe(max()).subscribe();
// Output: `3, 15, 100`

Filter

Operators for filtering Observable number sources for truthy queries

const source$ = from([1.4, 5, 8.2, 10, 12, 19, 11, 7.6, 14]);

// Gets numbers only in the range of `2` to `11`
source$.pipe(filterInRange(2, 11)).subscribe();
// Output: `5, 8.2, 10, 12, 11, 7.6`

// Gets numbers only in the range of `2` to `11`
source$.pipe(filterOutOfRange(2, 11)).subscribe();
// Output: `1.4, 19, 14`

// Get only floating numbers
source$.pipe(filterIsFloat()).subscribe();
// Output: `1.4, 8.2, 7.6`

Formatting

Operators for formatting numbers to strings

const floatSource$ = from([1.9875, 5.67, 8.1, 97.344]);

// Get a fixed length string
floatSource$.pipe(toFixed(2)).subscribe();
// Output: `'1.99', '5.67', '8.10', '97.34'`

// Format value to local currency
floatSource$.pipe(toLocaleString('en-GB', { currency: 'EUR', style: 'currency' })).subscribe();
// Output: `'€1.99', '€5.67', '€8.10', '€97.34'`

Math

Operators for some math operations such as add, subtract, multiply and raise by power

const source$ = from([1, 2, 3, 4, 5]);

// Add `5` to the source value
$source.pipe(add(5)).subscribe();
// Output: `6, 7, 8, 9, 10`

// Add `5` to the source value
$source.pipe(mul(2)).subscribe();
// Output: `2, 4, 6, 8, 10`

// Return the remainder for modulus 2
$source.pipe(mod(2)).subscribe();
// Output: `1, 0, 1, 0, 1`

Parsing

Operators for parsing strings to numbers

const floatSource$ = from(['1.9875', '5.67', '8.1', '97.344', 'Ninja']);

// Parse string values as float
floatSource$.pipe(parseFloat()).subscribe();
// Output: `1.9875, 5.67, 8.1, 97.344, NaN`

// Parse string values as integer
floatSource$.pipe(parseInt()).subscribe();
// Output: `1, 5, 8, 97, NaN`

Query

Operators for querying number sources for boolean checks

const source$ = from([1.4, 5, 8.2, NaN, 12, 19, 11, NaN, 14]);

// Check if number is in range of `2` to `11`
source$.pipe(inRange(2, 11)).subscribe();
// Output: `false, true, true, false, false, false, true, false, false`

// Check if values are not NaN values
source.pipe(isNotNaN()).subscribe();
// Output: `true, true, true, false, true, true, true, false, true`