validator.js

const jsdom = require("jsdom");
const _ = require("lodash");
const { JSDOM } = jsdom;

exports.domValidation = (htmlText, cssText, structure, validations) => {
    /*
    Check HTML and validate contents.
    Return if the HTML is valid. Otherwise state violated rules.
    */
    const {document} = (new JSDOM(htmlText)).window;

    //TODO: Apply CSS taking into account cssText passed:
    // 1. decode string
    // 2. create temp file and get absolute path to temp file (https://github.com/raszi/node-tmp)
    // 3. add link tag to head using absolute file path to temp file (https://github.com/jsdom/jsdom/issues/1495)
    // 4. check style of elements taking into account a selector (https://github.com/jsdom/jsdom/issues/1927)
    let styleSheet = document.createElement("style");
    styleSheet.setAttribute('type', 'text/css');
    const head = document.querySelector("head");
    head.appendChild(styleSheet);
    styleSheet = document.styleSheets[document.styleSheets.length - 1];


    let results = [];
    // Check page structure. Elements given in the other of the 'querySelectorAll("*")' return
    let validStructure = true;
    let causeStructure = '';
    const {rootSelector, elementsList} = structure;
    const rootElement = document.querySelector(rootSelector);
    validStructure = rootElement? true: false;

    if(validStructure){
        // TODO: Use  document.querySelector("rootSelector").querySelectorAll("*")
        // to get all elements children and children of children given node in the HTML 
        const elementsInOrder = Array.from(rootElement.querySelectorAll("*"))
                                        .map( el => { return el.tagName.toLowerCase()});
        validStructure = _.isEqual(elementsInOrder, elementsList);
        causeStructure = validStructure? `Structure [${elementsInOrder}] follows given structure [${elementsList}]`
                                        : `Structure [${elementsInOrder}] doesn't follow given structure [${elementsList}]`;
        results.push({rootSelector, validStructure, causeStructure});
    } else {
        causeStructure = `Couldn't find selector ${rootSelector} to start checking HTML structure.`;
        results.push({rootSelector, validStructure, causeStructure});   
    }
    // Check validations
    for(let validation of validations){
        try {
            let valid = true;
            let cause = '';
            const {selector = '*', expectedValues = []} = validation;                
            const elements = Array.from(document.querySelectorAll(selector));
    
            if (valid && expectedValues.length > 0) {
                for(let element of elements){
                    // TODO: Check expected values in each element, push to results validation
                    for(let rule of expectedValues){
                        const {attribute, value} = rule;
                        let elementAttribute = '';
                        let valid = true;
                        if (attribute === 'innerHTML'){
                            elementAttribute = element[attribute];
                        } else {
                            elementAttribute = element.getAttribute(attribute);
                            valid = elementAttribute === value;
                        }
                        if (attribute === 'class') {
                            // Compare value (list) with intersection of attribute class parsed as list and value (list)
                            elementAttribute = elementAttribute.split(' ');
                            valid = value.length === value.filter(ele => elementAttribute.includes(ele)).length;
                        }
                        cause = valid ? `Element '${selector}': attribute '${attribute}' has value '${value}'`: `Element '${selector}': attribute '${attribute}' has value '${elementAttribute}' instead of '${value}'`;
                        results.push({selector, valid, cause});
                    }
                }
            }                         
        } catch(err){
            console.log(err);
            return {
                valid: false,
                cause: err.toString()};
            }
    }
    return results;
}