Small and configurable full-text search on objects in TypeScript

matcher.ts

export type Matcher<T> = (query: string) => T[];

export type ValueProject<T> = (target: T) => Array<string | number>;

export type MatcherFactory = <T>(targets: T[], project: ValueProject<T>) => Matcher<T>;

export const defaultProject = <T>(target: T) => Object.values(target);
  
const isMatchable = prop => typeof prop == 'number' || typeof prop == 'string'
  
export const matcher: MatcherFactory = <T>(targets, project = defaultProject) => {
  const matchEntries: Array<[string, T]> = targets
    .map(target => {
      const matchString = project(target)
        .filter(property => property && isMatchable(property))
        .join('').toLowerCase();
      return [matchString, target];
    });
  return (query: string): T[] => {
    if (!query) {
      return targets;
    }
    const words = query.trim().toLowerCase().split(' ');
    return matchEntries
      .filter(([matchString, target]) => words
        .every(word => matchString.includes(word))
      )
      .map(([matchString, target]) => target);
  };
};

usage.ts

import { matcher } from './matcher';

interface User {
  id: number
  username: string
  mail: string
  company: {
    name: string
    address: string
  }
}

const users: User[] = [/* fill with users */]

const match = matcher(users, user => [
  // only match these properties
  user.id, user.username, user.mail, user.company.name
])

// returns every user containing both words in any of
// the configured properties
const result = match('Andrew Twi')

Cool work, thanks for sharing, I look forward to trying this one out sometime :)