enumerated-type

Small utility library implementing enum types that can be used in switch statements, can have an optional property used as the key for the enum values, have shared properties for all values and each enum value can have own properties.

Install

Use npm to install.

npm install enumerated-type --save

Usage

Use new Enum(enumName, values, commonProperties, keyPropName, labelPropName) to define an enum for given values. The property values of the values object can be objects/arrays/functions or non-objects.

Defining an enum using objects as values:

// NOTE: defining the enum using intermediate objects allows JetBrains IDEs completion to work better with enums and enum values
// common enum value properties, instance enum values can override these with their own definitions
const StepTypeValue = {
    stepTypeId: 0,
    isDuty: false,
    isVariable: false,
    isOptional: false,
    isGateway: false,
    isXor: false,
    isAnd: false,
    isCombined: false,
};

// NOTE: defining the enum using intermediate objects allows JetBrains IDEs completion to work better with enums and enum values
// enum value properties
let StepType = {
    duty: { stepTypeId: 1, isDuty: true, label: "Duty"},
    variable: { stepTypeId: 2, isVariable: true, label: "Variable"},
    optional: { stepTypeId: 3, isOptional: true, label: "Optional"},
    xor: { stepTypeId: 4, isGateway: true, isXor: true, label: "Xor"},
    and: { stepTypeId: 5, isGateway: true, isAnd: true, label: "And"},
    combineXor: { stepTypeId: 6, isGateway: true, isXor: true, isCombined: true, label: "Combine Xor"},
    combineAnd: { stepTypeId: 7, isGateway: true, isAnd: true, isCombined: true, label: "Combine And"},

    // this will be ignored and a function that resolves stepTypeId to Enum type will be used
    stepTypeId(value) {
        return StepTypeValue;
    },

    // this will be available as a function property of the enum, and will no be part of its values
    customFunction(works) {
        return `Yes, it ${works}!`;
    }
};

StepType = new Enum("StepType", StepType, StepTypeValue, "stepTypeId", "label");

commonProperties are used for each enum value for its prototype, therefore they provide a default value when the enum value does not define the property directly:

const values = [];
for (let value of StepType) {
    values.push({
        isAnd: value.isAnd,
        isCombined: value.isCombined,
        isDuty: value.isDuty,
        isGateway: value.isGateway,
        isOptional: value.isOptional,
        isVariable: value.isVariable,
        isXor: value.isXor,
        name: value.name,
        stepTypeId: value.stepTypeId,
    });
}

expect(values).toEqual([
    { "isAnd": false, "isCombined": false, "isDuty": true, "isGateway": false, "isOptional": false, "isVariable": false, "isXor": false, "name": "duty", "stepTypeId": 1, },
    { "isAnd": false, "isCombined": false, "isDuty": false, "isGateway": false, "isOptional": false, "isVariable": true, "isXor": false, "name": "variable", "stepTypeId": 2, },
    { "isAnd": false, "isCombined": false, "isDuty": false, "isGateway": false, "isOptional": true, "isVariable": false, "isXor": false, "name": "optional", "stepTypeId": 3, },
    { "isAnd": false, "isCombined": false, "isDuty": false, "isGateway": true, "isOptional": false, "isVariable": false, "isXor": true, "name": "xor", "stepTypeId": 4, },
    { "isAnd": true, "isCombined": false, "isDuty": false, "isGateway": true, "isOptional": false, "isVariable": false, "isXor": false, "name": "and", "stepTypeId": 5, },
    { "isAnd": false, "isCombined": true, "isDuty": false, "isGateway": true, "isOptional": false, "isVariable": false, "isXor": true, "name": "combineXor", "stepTypeId": 6, },
    { "isAnd": true, "isCombined": true, "isDuty": false, "isGateway": true, "isOptional": false, "isVariable": false, "isXor": false, "name": "combineAnd", "stepTypeId": 7, },
]);

Use enum values as property names:

let obj = {};
obj['duty'] = "++duty";
obj[StepType.duty] = "--duty";
obj[StepType.variable] = "--variable";
obj[StepType.optional] = "--optional";
obj[StepType.xor] = "--xor";
obj[StepType.and] = "--and";
obj[StepType.combineXor] = "--combineXor";
obj[StepType.combineAnd] = "--combineAnd";

expect(obj.duty).toEqual('++duty');

let values = [];
StepType.forEach(value => {
    values.push(obj[value]);
});

expect(values).toEqual([
    "--duty",
    "--variable",
    "--optional",
    "--xor",
    "--and",
    "--combineXor",
    "--combineAnd",
]);

Enum Instance Properties

• .name : name of the enum passed to constructor
• .values : array of enum values sorted by keyPropName if provided or by value if non-object values.
• dropdownChoices : an array of {value: xxx, label: yyy} where xxx is the keyPropName value and yyy is the labelPropName value from the enum values used during construction. If labelPropName is not given then the name of the property will be used.
• .keys : array of enum key properties if keyPropName was passed to constructor, otherwise array of enum values which were not objects
• [keyPropName](key): function taking key and returning enum value whose keyPropName equals the value of the key. Only defined if keyPropName is defined and is a string. Convenience method for converting key property value to an enum value.
• .value(key): function taking the a value and returning enum value whose value equals the key. Only defined if keyPropName is not defined. The function will pass enum values unmolested so it is safe to pass to it an enum value.
• .filter: function (callback, thisArg) taking a callback function(value, index, values) and returning array of values for which callback result tested true, unless callback returns BREAK(result) or RETURN(result). see for-each-break
• .forEach: function (callback, thisArg, defaultResult) taking a callback function(value, index, values) and optional default result if callback does not return BREAK(result) or RETURN(result). see for-each-break
• .map: function (callback, thisArg) taking a callback function(value, index, values) and returning array of values returned my callback, unless callback returns BREAK(result) or RETURN(result). see for-each-break
• .filterRight: function (callback, thisArg, thisArg) taking a callback function(value, index, values) and returning array of values for which callback result tested true, unless callback returns BREAK(result) or RETURN(result). see for-each-break
• .forEachRight: function (callback, thisArg, thisArg, defaultResult) taking a callback function(value, index, values) and optional default result if callback does not return BREAK(result) or RETURN(result). see for-each-break
• .mapRight: function (callback, thisArg, thisArg) taking a callback function(value, index, values) and returning array of values returned my callback, unless callback returns BREAK(result) or RETURN(result). see for-each-break
• [Symbol.iterator]: iterator over enum values
• [Symbol.hasInstance]: handles instanceof and returns true when left hand side is an enum value of this enum instance.
• .toString: returns [object Enum(enumName)]

Enum Value Instance Properties

In addition to enum value properties passed for the value each enum value has the following additional properties:

• .enum: parent enum instance.
• .name: name of the enum value (property name in values object passed to Enum() constructor.
• .value: Symbol(name) symbol instance for the property name of the enum value.
• .index: the enum value's index within enum instances values array.
• .next: enum value after this enum or undefined if last enum value.
• .previous: enum value before this enum or undefined if first enum value.
• [Symbol.toPrimitive]: returns value property for string or default hint, for number returns the enum value's index within enum instances values array.

⚠️ Functions passed in as property values for enum value properties or commonProperties will have this set to the enum value instance.

⚠️ Any functions which take no arguments (ie. function.length === 0) will be converted to getters of the enum value instance and should not use the function call syntax.

License

MIT, see LICENSE.md for details.