hello.js

'use strict';

var arrayutil = require('./arrayutil');

var domutil = {
    getElementsByClassName: function(element, selector) {
        if (!selector) {
            throw new Error('Uncaught TypeError: Failed to execute "getElementsByClassName": 1 argument required, but only 0 present.');
        }

        if (!element.getElementsByClassName) {
            element.getElementsByClassName = function(query) {
                return element.querySelectorAll('.' + query);
            };
        }

        return Array.prototype.slice.call(document.getElementsByClassName(selector));
    },
    getElementById: function(element, selector) {
        return element.getElementById(selector);
    },
    getElementsByTagName: function(element, selector) {
        return Array.prototype.slice.call(element.getElementsByTagName(selector));
    },
    querySelector: function(selector) {
        var result = domutil.querySelectorAll(selector);

        return result.length > 0 ? result[0] : null;
    },
    querySelectorAll: function(selector) {
        var selectorArr = [],
            firstNodes = [],
            retFirstNodes = [],
            resultNodes = [],
            multipleQueryArr = [],
            firstNodesLen,
            queryType,
            query,
            queryArrLen,
            node,
            i,
            customQuerySelectorAll,
            getFirstNodes,
            selectorArrLen;

        if (!selector) {
            throw new Error('Uncaught TypeError: Failed to execute "querySelector": 1 argument required, but only 0 present.');
        }
        selectorArr = selector.split(' ');
        selectorArrLen = selectorArr.length;
        for (i = 0; i < selectorArrLen; i += 1) {
            selectorArr[i] = arrayutil.removeEmptyString(selectorArr[i].replace('.', ' .').replace('#', ' #').split(' '));
            if (!this.isValidMultipleSelector(selectorArr[i])) {
                throw new Error('Failed to execute "querySelector": ' + selectorArr[i] + ' is not a valid selector.');
            }
        }

        getFirstNodes = function(queryArr) {
            multipleQueryArr = queryArr[queryArrLen - 1];
            query = multipleQueryArr[0];

            queryType = domutil.getSelectorType(query);
            if (queryType === 'class') {
                firstNodes = domutil.getElementsByClassName(document, query.slice(1));
            } else if (queryType === 'id') {
                firstNodes = new Array(domutil.getElementById(document, query.slice(1)));
            } else {
                firstNodes = domutil.getElementsByTagName(document, query);
            }
            for (i = 0; i < firstNodes.length; i += 1) {
                if (domutil.isMatchToAllQueiresNode(firstNodes[i], multipleQueryArr, 1)) {
                    retFirstNodes.push(firstNodes[i]);
                }
            }

            return retFirstNodes;
        };

        customQuerySelectorAll = function(queryArr) {
            queryArrLen = queryArr.length;
            firstNodes = getFirstNodes(queryArr);
            if (queryArrLen > 1) {
                firstNodesLen = firstNodes.length;
                for (i = 0; i < firstNodesLen; i += 1) {
                    node = firstNodes[i];
                    if (domutil.isMatchingToQueriesNode(node.parentNode, queryArr)) {
                        resultNodes.push(node);
                    }
                }
            } else {
                resultNodes = firstNodes;
            }

            return arrayutil.removeDuplicates(resultNodes);
        };

        return customQuerySelectorAll(selectorArr);
    },
    getSelectorType: function(selector) {
        var type;
        switch (selector[0]) {
            case '#':
                type = 'id';
                break;
            case '.':
                type = 'class';
                break;
            default:
                type = 'tag';
        }

        return type;
    },
    isMatchToAllQueiresNode: function(node, queryArr, startIdx) {
        var i,
            queryArrLen = queryArr.length,
            result = true;
        for (i = startIdx; i < queryArrLen; i += 1) {
            result = domutil.isMatchToQueryNode(node, queryArr[i]) && result;
        }

        return result;
    },
    isMatchToQueryNode: function(node, query) {
        var queryType = domutil.getSelectorType(query);

        if (queryType === 'class') {
            return domutil.isNodeHavingClass(node, query.slice(1));
        }

        return queryType === 'id' ? domutil.isNodeHavingId(node, query.slice(1)) : domutil.isNodeHavingTagName(node, query);
    },
    isNodeHavingClass: function(node, className) {
        var re = new RegExp('\\b\\*?' + className + '*\\b', 'g');

        return re.test(node.className);
    },
    isNodeHavingId: function(node, id) {
        return node.id === id;
    },
    isNodeHavingTagName: function(node, tagName) {
        return node.tagName.toLowerCase() === tagName.toLowerCase();
    },
    isMatchingToQueriesNode: function(node, queryArr) {
        var queryArrLen = queryArr.length,
            query,
            matchToQuery,
            queryArrIdx = queryArrLen - 2;
        while (node.parentNode !== null) {
            query = queryArr[queryArrIdx];
            matchToQuery = domutil.isMatchToAllQueiresNode(node, query, 0);
            node = node.parentNode;
            if (queryArrIdx === 0 && matchToQuery) {
                break;
            }
            if (matchToQuery) {
                queryArrIdx -= 1;
            }
        }

        return queryArrIdx === 0 && matchToQuery;
    },
    isValidSelector: function(selector) {
        var re = /^[$,.,#,_0-9a-zA-Z]{0,1}[a-zA-Z0-9-_]{1}[#.a-zA-Z0-9-_]{0,}/;

        return re.test(selector);
    },
    isValidMultipleSelector: function(selectorArr) {
        var i;
        for (i = 0; i < selectorArr.length; i += 1) {
            if (!this.isValidSelector(selectorArr[i])) {
                return false;
            }
        }

        return true;
    }
};

module.exports = domutil;