Migrate examples to typescript

Author: chris-pardy

examples/01-hello-world.js renamed to examples/01-hello-world.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This is the hello-world example from the README.
  *
@@ -9,8 +8,8 @@
  *   DEBUG=json-rules-engine node ./examples/01-hello-world.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
+import "colors";
+import { Engine } from "json-rules-engine";
 
 async function start() {
   /**
@@ -51,7 +50,7 @@ async function start() {
   // engine.run() evaluates the rule using the facts provided
   const { events } = await engine.run(facts);
 
-  events.map((event) => console.log(event.params.data.green));
+  events.map((event) => console.log(event.params!.data.green));
 }
 
 start();

examples/02-nested-boolean-logic.js renamed to examples/02-nested-boolean-logic.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This example demonstates nested boolean logic - e.g. (x OR y) AND (a OR b).
  *
@@ -9,8 +8,8 @@
  *   DEBUG=json-rules-engine node ./examples/02-nested-boolean-logic.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
+import "colors";
+import { Engine } from "json-rules-engine";
 
 async function start() {
   /**
@@ -77,7 +76,7 @@ async function start() {
 
   const { events } = await engine.run(facts);
 
-  events.map((event) => console.log(event.params.message.red));
+  events.map((event) => console.log(event.params!.message.red));
 }
 start();
 /*

examples/03-dynamic-facts.js renamed to examples/03-dynamic-facts.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This example demonstrates computing fact values at runtime, and leveraging the 'path' feature
  * to select object properties returned by facts
@@ -10,11 +9,11 @@
  *   DEBUG=json-rules-engine node ./examples/03-dynamic-facts.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
+import "colors";
+import { Engine } from "json-rules-engine";
 
 // example client for making asynchronous requests to an api, database, etc
-const apiClient = require("./support/account-api-client");
+import apiClient from "./support/account-api-client.mjs";
 
 async function start() {
   /**
@@ -65,18 +64,17 @@ async function start() {
    * into the engine.  The major advantage of this technique is that although there are THREE conditions
    * requiring this data, only ONE api call is made.  This results in much more efficient runtime performance.
    */
-  engine.addFact("account-information", function (params, almanac) {
-    return almanac.factValue("accountId").then((accountId) => {
-      return apiClient.getAccountInformation(accountId);
-    });
+  engine.addFact("account-information", async function (_params, almanac) {
+    const accountId = await almanac.factValue<string>("accountId");
+    return apiClient.getAccountInformation(accountId);
   });
 
   // define fact(s) known at runtime
   const facts = { accountId: "lincoln" };
   const { events } = await engine.run(facts);
 
   console.log(
-    facts.accountId + " is a " + events.map((event) => event.params.message),
+    facts.accountId + " is a " + events.map((event) => event.params!.message),
   );
 }
 start();

examples/04-fact-dependency.js renamed to examples/04-fact-dependency.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This is an advanced example that demonstrates facts with dependencies
  * on other facts.  In addition, it demonstrates facts that load data asynchronously
@@ -11,9 +10,9 @@
  *   DEBUG=json-rules-engine node ./examples/04-fact-dependency.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
-const accountClient = require("./support/account-api-client");
+import "colors";
+import { Engine } from "json-rules-engine";
+import accountClient from "./support/account-api-client.mjs";
 
 async function start() {
   /**
@@ -72,7 +71,7 @@ async function start() {
   /**
    * Register listeners with the engine for rule success and failure
    */
-  let facts;
+  let facts: Record<string, unknown>;
   engine
     .on("success", (event) => {
       console.log(
@@ -98,31 +97,33 @@ async function start() {
    * 'account-information' fact executes an api call and retrieves account data
    * - Demonstrates facts called only by other facts and never mentioned directly in a rule
    */
-  engine.addFact("account-information", (params, almanac) => {
-    return almanac.factValue("accountId").then((accountId) => {
-      return accountClient.getAccountInformation(accountId);
-    });
+  engine.addFact("account-information", async (_params, almanac) => {
+    const accountId = await almanac.factValue<string>("accountId");
+    return accountClient.getAccountInformation(accountId);
   });
 
   /**
    * 'employee-tenure' fact retrieves account-information, and computes the duration of employment
    * since the account was created using 'accountInformation.createdAt'
    */
-  engine.addFact("employee-tenure", (params, almanac) => {
-    return almanac
-      .factValue("account-information")
-      .then((accountInformation) => {
-        const created = new Date(accountInformation.createdAt);
-        const now = new Date();
-        switch (params.unit) {
-          case "years":
-            return now.getFullYear() - created.getFullYear();
-          case "milliseconds":
-          default:
-            return now.getTime() - created.getTime();
-        }
-      })
-      .catch(console.log);
+  engine.addFact("employee-tenure", async (params, almanac) => {
+    try {
+      const accountInformation = await almanac.factValue<{ createdAt: string }>(
+        "account-information",
+      );
+      const created = new Date(accountInformation.createdAt);
+      const now = new Date();
+      switch (params.unit) {
+        case "years":
+          return now.getFullYear() - created.getFullYear();
+        case "milliseconds":
+        default:
+          return now.getTime() - created.getTime();
+      }
+    } catch (err) {
+      console.log(err);
+      return undefined;
+    }
   });
 
   // first run, using washington's facts

examples/05-optimizing-runtime-with-fact-priorities.js renamed to examples/05-optimizing-runtime-with-fact-priorities.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This is an advanced example that demonstrates using fact priorities to optimize the rules engine.
  *
@@ -9,9 +8,9 @@
  *   DEBUG=json-rules-engine node ./examples/05-optimizing-runtime-with-fact-priorities.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
-const accountClient = require("./support/account-api-client");
+import "colors";
+import { Engine } from "json-rules-engine";
+import accountClient from "./support/account-api-client.mjs";
 
 async function start() {
   /**
@@ -81,12 +80,11 @@ async function start() {
    */
   engine.addFact(
     "account-information",
-    (params, almanac) => {
+    async (_params, almanac) => {
       // this fact will not be evaluated, because the "date" fact will fail first
       console.log('Checking the "account-information" fact...'); // this message will not appear
-      return almanac.factValue("accountId").then((accountId) => {
-        return accountClient.getAccountInformation(accountId);
-      });
+      const accountId = await almanac.factValue<string>("accountId");
+      return accountClient.getAccountInformation(accountId);
     },
     { priority: LOW },
   );
@@ -97,7 +95,7 @@ async function start() {
    */
   engine.addFact(
     "date",
-    (params, almanac) => {
+    () => {
       console.log('Checking the "date" fact...');
       return Date.now();
     },

examples/06-custom-operators.js renamed to examples/06-custom-operators.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This example demonstrates using custom operators.
  *
@@ -15,8 +14,8 @@
  *   DEBUG=json-rules-engine node ./examples/06-custom-operators.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
+import "colors";
+import { Engine } from "json-rules-engine";
 
 async function start() {
   /**
@@ -27,7 +26,7 @@ async function start() {
   /**
    * Define a 'startsWith' custom operator, for use in later rules
    */
-  engine.addOperator("startsWith", (factValue, jsonValue) => {
+  engine.addOperator("startsWith", (factValue: string, jsonValue: string) => {
     if (!factValue.length) return false;
     return factValue[0].toLowerCase() === jsonValue.toLowerCase();
   });
@@ -71,15 +70,15 @@ async function start() {
   engine.addRule(ruleB);
 
   // utility for printing output
-  const printEventType = {
+  const printEventType: Record<string, string> = {
     "start-with-a": 'start with "a"',
     "start-with-b": 'start with "b"',
   };
 
   /**
    * Register listeners with the engine for rule success and failure
    */
-  let facts;
+  let facts: Record<string, unknown>;
   engine
     .on("success", (event) => {
       console.log(facts.word + " DID ".green + printEventType[event.type]);

examples/07-rule-chaining.js renamed to examples/07-rule-chaining.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This is an advanced example demonstrating rules that passed based off the
  * results of other rules by adding runtime facts.  It also demonstrates
@@ -11,9 +10,9 @@
  *   DEBUG=json-rules-engine node ./examples/07-rule-chaining.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
-const { getAccountInformation } = require("./support/account-api-client");
+import "colors";
+import { Almanac, Engine } from "json-rules-engine";
+import apiClient from "./support/account-api-client.mjs";
 
 async function start() {
   /**
@@ -41,16 +40,16 @@ async function start() {
     },
     event: { type: "drinks-screwdrivers" },
     priority: 10, // IMPORTANT!  Set a higher priority for the drinkRule, so it runs first
-    onSuccess: async function (event, almanac) {
+    onSuccess: async function (_event: unknown, almanac: Almanac) {
       almanac.addFact("screwdriverAficionado", true);
 
       // asychronous operations can be performed within callbacks
       // engine execution will not proceed until the returned promises is resolved
-      const accountId = await almanac.factValue("accountId");
-      const accountInfo = await getAccountInformation(accountId);
+      const accountId = await almanac.factValue<string>("accountId");
+      const accountInfo = await apiClient.getAccountInformation(accountId);
       almanac.addFact("accountInfo", accountInfo);
     },
-    onFailure: function (event, almanac) {
+    onFailure: function (_event: unknown, almanac: Almanac) {
       almanac.addFact("screwdriverAficionado", false);
     },
   };
@@ -92,7 +91,9 @@ async function start() {
    */
   engine
     .on("success", async (event, almanac) => {
-      const accountInfo = await almanac.factValue("accountInfo");
+      const accountInfo = await almanac.factValue<{ company: string }>(
+        "accountInfo",
+      );
       const accountId = await almanac.factValue("accountId");
       console.log(
         `${accountId}(${accountInfo.company}) ` +
@@ -122,7 +123,7 @@ async function start() {
   let results = await engine.run(facts);
 
   // isScrewdriverAficionado was a fact set by engine.run()
-  let isScrewdriverAficionado = results.almanac.factValue(
+  let isScrewdriverAficionado = await results.almanac.factValue<boolean>(
     "screwdriverAficionado",
   );
   console.log(

examples/08-fact-comparison.js renamed to examples/08-fact-comparison.mts

@@ -1,4 +1,3 @@
-"use strict";
 /*
  * This is a basic example demonstrating a condition that compares two facts
  *
@@ -9,8 +8,8 @@
  *   DEBUG=json-rules-engine node ./examples/08-fact-comparison.js
  */
 
-require("colors");
-const { Engine } = require("json-rules-engine");
+import "colors";
+import { Engine } from "json-rules-engine";
 
 async function start() {
   /**
@@ -52,36 +51,35 @@ async function start() {
   };
   engine.addRule(rule);
 
-  engine.addFact("account", (params, almanac) => {
+  engine.addFact("account", async (params, almanac) => {
     // get account list
-    return almanac.factValue("accounts").then((accounts) => {
-      // use "params" to filter down to the type specified, in this case the "customer" account
-      const customerAccount = accounts.filter(
-        (account) => account.type === params.accountType,
-      );
-      // return the customerAccount object, which "path" will use to pull the "balance" property
-      return customerAccount[0];
-    });
+    const accounts = await almanac.factValue<{ type: string }[]>("accounts");
+    // use "params" to filter down to the type specified, in this case the "customer" account
+    const customerAccount = accounts.filter(
+      (account) => account.type === params.accountType,
+    );
+    // return the customerAccount object, which "path" will use to pull the "balance" property
+    return customerAccount[0];
   });
 
-  engine.addFact("product", (params, almanac) => {
+  engine.addFact("product", async (params, almanac) => {
     // get product list
-    return almanac.factValue("products").then((products) => {
-      // use "params" to filter down to the product specified, in this case the "giftCard" product
-      const product = products.filter(
-        (product) => product.productId === params.productId,
-      );
-      // return the product object, which "path" will use to pull the "price" property
-      return product[0];
-    });
+    const products =
+      await almanac.factValue<{ productId: string }[]>("products");
+    // use "params" to filter down to the product specified, in this case the "giftCard" product
+    const product = products.filter(
+      (product) => product.productId === params.productId,
+    );
+    // return the product object, which "path" will use to pull the "price" property
+    return product[0];
   });
 
   /**
    * Register listeners with the engine for rule success and failure
    */
-  let facts;
+  let facts: Record<string, unknown>;
   engine
-    .on("success", (event, almanac) => {
+    .on("success", (event) => {
       console.log(
         facts.userId +
           " DID ".green +