RxJS Ninja - Strings

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

Function and Operator categories

Convert

Convert between String and Array values

// Split comma-seperated list into tab seperated list
of('Jane,Rod,Freddy,George').pipe(split(','), join('\t')).subscribe();
// Output: `'Jane\tRod\tFreddy\tGeorge'`

Create

Functions to create strings from various input

// Create a string from an array of codepoints
fromCodePoint([9731, 9733, 9842]).subscribe();
// Output: `'☃★♲'`

Filter

Operators for filtering string based on passed conditions

const source$ = from(['RxJS', 'TypeScript', 'Angular', 'HorseJS', 'JS Weekly']);

// Get items from the source that only end in `JS`
source$.pipe(filterStartsWith('JS')).subscribe();
// Output: `'JS Weekly'`

// Get items from the source that only end in `JS`
source$.pipe(filterEndsWith('JS')).subscribe();
// Output: `'RxJS', 'HorseJS'`

Mapping

Operators for mapping codes to String values

// Get the string character for a code point
from([9731, 9733, 9842]).pipe(mapCodePoint()).subscribe();
// Output: `'☃', '★', '♲'`

Modify

Operators for modifying String values

const source$ = from(['RxJS', 'Angular', 'TypeScript', 'jQuery']);

// Concat to an string
source$.pipe(concat(' is cool')).subscribe();
// Output: `'RxJS is cool', 'Angular is cool', 'TypeScript is cool', 'jQuery is cool'`

source$.pipe(reverse()).subscribe();
// Output: `'SJxR', 'ralugnA', 'tpircSepyT`, 'yreuQj'`

Query

Operators for querying String values and returning a value based on a boolean check

• Query - Operators that return non-string values based on querying string values

const source$ = from(['RxJS', 'TypeScript', 'Angular', 'HorseJS', 'JS Weekly']);

// Check the string starts with `JS`
source$.pipe(startWith('JS')).subscribe();
// Output: `false, false, false, false, true`

// Check the string ends with `JS`
source$.pipe(endsWith('JS')).subscribe();
// Output: `true, false, false, true, false`