rule-apparatus v1.0.3

Rule-Apparatus

A simple rule engine

Installation

npm i rule-apparatus

Usage

Definition:

interface Input {
    input1: string | null;
    input2: string | null;
}

interface Output {
    flag1: boolean | null;
    flag2: boolean | null;
}

interface Rule {
    input: Input;
    output: Output;
}

Evaluation:

const ruleDefinitions: Rule[] = [
    {input: {input1: 'hello', input2: 'world'}, output: {flag1: true, flag2: true}},
    {input: {input1: null, input2: 'world'}, output: {flag1: false, flag2: true}},
    {input: {input1: 'hello', input2: null}, output: {flag1: true, flag2: false}},
    {input: {input1: null, input2: null}, output: {flag1: false, flag2: false}},
];

evaluate<Input, Output>(ruleDefinitions, {input1: 'hello', input2: 'world'});
// { flag1: true, flag2: true }

Another example

interface Input {
    universityDegree: 'NONE' | 'BACHELOR' | 'MASTER';
    minimumYearsOfExperience: 0 | 2 | 5 | 8 | 10 | 15;
    hasBlog: boolean;
    lastYearsPerformance: 1 | 2 | 3 | 4 | 5;
}

interface Output {
    minSalary: number;
    maxSalary: number;
}

interface Rule {
    input: Input;
    output: Output;
}

const ruleDefinitions: Rule[] = [
    {
        input: { universityDegree: 'MASTER', minimumYearsOfExperience: 8, hasBlog: false, lastYearsPerformance: 3 },
        output: { minSalary: 120_000, maxSalary: 130_000 }
    },
    {
        input: { universityDegree: 'NONE', minimumYearsOfExperience: 10, hasBlog: true, lastYearsPerformance: 4 },
        output: { minSalary: 125_000, maxSalary: 135_000 }
    }
];


let candidateA: Input = { universityDegree: 'MASTER', minimumYearsOfExperience: 8, hasBlog: false, lastYearsPerformance: 3 };
let candidateB: Input = { universityDegree: 'NONE', minimumYearsOfExperience: 10, hasBlog: true, lastYearsPerformance: 4 };

expect(evaluate<Input, Output>(ruleDefinitions, candidateA)).toEqual({
    minSalary: 120_000,
    maxSalary: 130_000,
});
expect(evaluate<Input, Output>(ruleDefinitions, candidateB)).toEqual({
    minSalary: 125_000,
    maxSalary: 135_000,
});