node-rules/examples/node.js/4.PrioritizedRules.js

Business Rules Engine for JavaScript

import RuleEngine from '../../lib/node-rules.js';

/* Set of Rules to be applied */
var rules = [{
    "priority": 4,
    "condition": function(R) {
        R.when(this.transactionTotal < 500);
    },
    "consequence": function(R) {
        this.result = false;
        this.reason = "The transaction was blocked as it was less than 500";
        R.stop();
    }
}, {
    "priority": 10, // this will apply first
    "condition": function(R) {
        R.when(this.cardType === "Debit");
    },
    "consequence": function(R) {
        this.result = false;
        this.reason = "The transaction was blocked as debit cards are not allowed";
        R.stop();
    }
}];
/* Creating Rule Engine instance and registering rule */
var R = new RuleEngine();
R.register(rules);
/* Fact with more than 500 as transaction but a Debit card, and this should be blocked */
var fact = {
    "name": "user4",
    "application": "MOB2",
    "transactionTotal": 600,
    "cardType": "Debit"
};
/* This fact will be blocked by the Debit card rule as its of more priority */
R.execute(fact, function(data) {
    if (data.result) {
        console.log("Valid transaction");
    } else {
        console.log("Blocked Reason:" + data.reason);
    }
});