flut1/knockout-validator

import Field from "../fields/Field";

/**
 * The DOM attribute key used to save an id of a Field
 */
const ID_DOM_ATTRIBUTE = 'data-ko-validator-id';

/**
 * Util that keeps track of all registered knockout-validator fields in your application.
 * Only the exported elementMapper singleton instance should be used, this class is exported
 * for testing purposes.
 */
export class ElementMapper
{
    /**
     * Counter to assign unique ids to each validator
     */
    private _idCounter:number = 1;

    /**
     * Static map of each field by id. Is used to lookup fields based on the id saved
     * on the corresponding HTML element.
     */
    private _fields:{[id:string]:Field} = {};

    /**
     * Generates a new id for an HTML element and sets it as an attribute on the element
     * @param element The element to generate an id for
     * @returns The generated id
     */
    public setElementId = (element:HTMLElement):string =>
    {
        const id = (this._idCounter++).toString();
        element.setAttribute(ID_DOM_ATTRIBUTE, id);
        return id;
    };

    /**
     * Gets the validator id of an HTML element
     * @param element The HTML element
     * @returns The id, or null if it is not set
     */
    public getElementId = (element:HTMLElement):string =>
    {
        return element.getAttribute(ID_DOM_ATTRIBUTE) || null;
    };

    /**
     * Creates a new field and stores it in the [[fields]] map so it can be saved for later
     * retrieval.
     * @param id
     * @param element
     * @returns {Field}
     */
    public createField = (id:string, element:HTMLElement = null):Field =>
    {
        this._fields[id] = new Field(id, element);
        return this._fields[id];
    };

    /**
     * Gets a Field instance with the given id
     * @param id The id to lookup
     * @returns The field instance. null if no such field instance exists
     */
    public getField = (id:string):Field =>
    {
        return this._fields[id] || null;
    };

    /**
     * Removes a field with the given id from the internal map of fields
     * @param id The id of the field to remove
     */
    removeField = (id:string):void =>
    {
        if(!this._fields[id])
        {
            throw new Error(`Trying to remove a field with non-existing id "${id}"`);
        }
        this._fields[id] = null;
    }
}

/**
 * Singleton element mapper instance to maintain global state of all knockout-validator
 * elements.
 */
const elementMapper = new ElementMapper();

export default elementMapper;