Initial working version

Author: ognus

.editorconfig

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+root = true
+
+[*]
+indent_size = 2

.gitignore

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+node_modules
+dist
+.vscode
+.cache
+examples

README.md

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 # filtersjs
+
 Simple faceted search solution for small JSON datasets.
+
+## Installation
+
+`yarn` or `npm install`
+
+## Usage
+
+```javascript
+// import or require filtersjs
+import { FiltersJS, Operation } from "filtersjs";
+
+// data to filter
+const items = [
+  {
+    name: "Scot",
+    gender: "Male",
+    age: 18,
+    card: ["jcb", "visa", "mastercard"]
+  },
+  {
+    name: "Seana",
+    gender: "Female",
+    age: 21,
+    card: ["jcb", "visa"]
+  },
+  {
+    name: "Ken",
+    gender: "Male",
+    age: 45,
+    card: ["jcb", "visa"]
+  },
+  {
+    name: "Boony",
+    gender: "Male",
+    age: 47,
+    card: ["visa"]
+  },
+  {
+    name: "Mike",
+    gender: "Male",
+    age: 67,
+    card: ["jcb", "visa"]
+  }
+];
+
+/**
+ * Options object with filters definitions. By default values are converted to lower case strings before match, for custom
+ * comparator provide a isMatching(val) function.
+ */
+const options = {
+  filters: [
+    { key: "card", value: "jcb" },
+    { key: "card", value: "mastercard" },
+    { key: "card", value: "visa" },
+    { key: "gender", value: "male" },
+    { key: "gender", value: "female" },
+    {
+      key: "age",
+      value: "18-25",
+      isMatching: v => 18 <= v && v <= 25
+    },
+    {
+      key: "age",
+      value: "25-50",
+      isMatching: v => 25 <= v && v <= 50
+    },
+    { key: "age", value: ">50", isMatching: v => 50 < v }
+  ]
+};
+
+// create a FiltersJS instance
+const filtersJS = new FiltersJS(items, options);
+
+// call search by providing current filters values
+const { results, filters } = filtersJS.search({
+  card: { values: ["jcb", "visa"], operation: Operation.And },
+  gender: "male",
+  age: ["18-25", "25-50"]
+});
+
+// filtered results
+console.log(results);
+// Prints:
+// {
+//   name: "Scot",
+//   gender: "Male",
+//   age: 18,
+//   card: ["jcb", "visa", "mastercard"]
+// },
+// {
+//   name: "Ken",
+//   gender: "Male",
+//   age: 45,
+//   card: ["jcb", "visa"]
+// }
+
+/**
+ * Active filters with number of results for each filter (if it will be applied).
+ * Can be used for basic facating and hiding filters that won't produce any results.
+ */
+console.log(filters);
+// Prints:
+// {
+//   card: { mastercard: 3 },
+//   gender: { female: 3 },
+//   age: { ">50": 3 }
+// }
+```

jest.config.js

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+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+};

package.json

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+{
+  "name": "filtersjs",
+  "version": "1.0.0",
+  "description": "Simple faceted search solution for small JSON datasets.",
+  "main": "src/index.ts",
+  "repository": "git@github.com:ognus/filtersjs.git",
+  "author": "Tomek Kolasa <kolasa.tomek@gmail.com>",
+  "license": "MIT",
+  "devDependencies": {
+    "@types/jest": "^24.0.15",
+    "jest": "^24.8.0",
+    "parcel-bundler": "^1.12.3",
+    "ts-jest": "^24.0.2",
+    "typescript": "^3.5.3"
+  },
+  "scripts": {
+    "dev": "parcel src/index.ts",
+    "test": "jest"
+  }
+}

src/DataProvider.ts

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+type Item = object;
+
+type WithId = [number, Item];
+
+export type FilterCallback = (
+  item: WithId,
+  idx: number,
+  array: IDataProvider
+) => boolean;
+
+export type MapCallback = (
+  item: WithId,
+  idx: number,
+  array: IDataProvider
+) => any;
+
+export interface IDataProvider {
+  length: number;
+  get: (id: string | number) => Item;
+  filter: (cb: FilterCallback) => IDataProvider;
+  map: (cb: MapCallback) => any[];
+}

src/Factory.ts

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+import { Finder, EOperation } from "./Finder";
+import { IndexStore } from "./IndexStore";
+import { MutableItemsStore } from "./ItemsStore";
+import { IDataProvider } from "./DataProvider";
+import { ISearchProvider, TFilter } from "./SearchProvider";
+
+export class Factory {
+  private dataStore: IDataProvider;
+
+  constructor(items: object[]) {
+    this.dataStore = new MutableItemsStore(items);
+  }
+
+  getSearchProvider(filters: TFilter[]): ISearchProvider {
+    const index = new IndexStore(this.dataStore);
+    filters.forEach(filter => index.add(filter));
+    return index;
+  }
+
+  getFinder(index: ISearchProvider, operations: { [key: string]: EOperation }) {
+    return new Finder(index, this.dataStore, operations);
+  }
+}

src/Finder.ts

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+import { ISearchProvider, TTerm } from "./SearchProvider";
+import { IDataProvider } from "./DataProvider";
+
+export enum EOperation {
+  And = "AND",
+  Or = "OR"
+}
+
+export class Finder {
+  constructor(
+    private search: ISearchProvider,
+    private data: IDataProvider,
+    private operations: { [key: string]: EOperation }
+  ) {}
+
+  private isMatching(
+    itemId: number,
+    propertyKey: string,
+    values: (string | number)[]
+  ) {
+    const operation = this.operations[propertyKey];
+
+    if (operation === EOperation.And) {
+      return values.every(value =>
+        this.search.isMatching(itemId, propertyKey, value)
+      );
+    }
+
+    return values.some(value =>
+      this.search.isMatching(itemId, propertyKey, value)
+    );
+  }
+
+  private getGroupedTerms(terms: TTerm[]) {
+    const termsByKey: { [key: string]: (string | number)[] } = terms.reduce(
+      (byKey, { key, value }) => {
+        byKey[key] = byKey[key] || [];
+        byKey[key].push(value);
+        return byKey;
+      },
+      {}
+    );
+
+    return Object.entries(termsByKey);
+  }
+
+  find(terms: TTerm[]): IDataProvider {
+    const grouped = this.getGroupedTerms(terms);
+
+    return this.data.filter(([itemId]) => {
+      return grouped.every(([key, values]) =>
+        this.isMatching(itemId, key, values)
+      );
+    });
+  }
+}

src/IndexStore.ts

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+import { IDataProvider } from "./DataProvider";
+import {
+  ISearchProvider,
+  TTerm,
+  TMatchingFunction,
+  TFilter
+} from "./SearchProvider";
+
+function defaultMatchingFunction(value: string | number) {
+  return (
+    new String(this.value.toLowerCase()).toLowerCase() ===
+    new String(value).toLowerCase()
+  );
+}
+
+class FilterOption implements TTerm {
+  private itemKey: string;
+  private optionValue: string | number;
+  private isMatchingFn: TMatchingFunction;
+
+  constructor(
+    itemKey: string,
+    optionValue: string | number,
+    isMatchingFn?: TMatchingFunction
+  ) {
+    this.itemKey = itemKey;
+    this.optionValue = optionValue;
+    this.isMatchingFn = isMatchingFn || defaultMatchingFunction.bind(this);
+  }
+
+  private getValues(item = {}) {
+    const value = item[this.itemKey];
+    return Array.isArray(value) ? value : [value];
+  }
+
+  isMatching(item: object) {
+    return this.getValues(item).some(value => this.isMatchingFn(value));
+  }
+
+  get value() {
+    return this.optionValue;
+  }
+
+  get key() {
+    return this.itemKey;
+  }
+}
+
+export class IndexStore implements ISearchProvider {
+  private index: {
+    [itemKey: string]: { [optionValue: string]: IDataProvider };
+  } = {};
+  private options: FilterOption[] = [];
+
+  constructor(private items: IDataProvider) {}
+
+  add({ key, value, isMatching }: TFilter) {
+    const option = new FilterOption(key, value, isMatching);
+    this.options.push(option);
+    this.index[key] = this.index[key] || {};
+    this.index[key][value] = this.items.filter(([, item]) =>
+      option.isMatching(item)
+    );
+  }
+
+  isMatching(
+    itemId: string | number,
+    propertyKey: string,
+    optionValue: string | number
+  ) {
+    return !!this.index[propertyKey][optionValue].get(itemId);
+  }
+
+  getTerms(): TTerm[] {
+    return this.options;
+  }
+}

src/ItemsStore.ts

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+import { IDataProvider, FilterCallback, MapCallback } from "./DataProvider";
+
+export class ItemsStore implements IDataProvider {
+  protected itemsById: { [id: number]: object } = {};
+  protected items: [number, object][] = [];
+
+  constructor(items: [number, object][]) {
+    this.items = items;
+    this.itemsById = Object.fromEntries(items);
+  }
+
+  get(id: string | number) {
+    return this.itemsById[id];
+  }
+
+  filter(precicate: FilterCallback) {
+    return new ItemsStore(
+      this.items.filter((itemWithId, idx) => precicate(itemWithId, idx, this))
+    );
+  }
+
+  map(iterator: MapCallback) {
+    return this.items.map((itemWithId, idx) => iterator(itemWithId, idx, this));
+  }
+
+  get length() {
+    return this.items.length;
+  }
+}
+
+export class MutableItemsStore extends ItemsStore {
+  private lastItemId = 0;
+
+  constructor(items: object[]) {
+    super([]);
+    items.forEach(item => this.add(item));
+  }
+
+  add(item: object) {
+    if (item) {
+      const id = ++this.lastItemId;
+      this.itemsById[id] = item;
+      this.items.push([id, item]);
+      return id;
+    }
+
+    return -1;
+  }
+}