比较两个文本的相似度

compare.js

var compare = (function () {
    "use strict";

    var splitText = function (text) {
        var map = {}, word = "", prevType = "";

        var typeList = {
            'number': /[-0-9\.]/,
            'alphabet': /[-'A-Z]/i,
            'han': /[\u4E00-\u9FA5]/
        };

        var blockList = /^[0-9的呢了]$/;

        text += " ";

        var i = 0, j = 0, char = "", nowType = "";
        for (i = 0; i < text.length; i++) {
            char = text.charAt(i).toLowerCase();

            nowType = "";
            for (j in typeList) {
                if (typeList[j].test(char)) {
                    nowType = j;
                    break;
                }
            }

            if (prevType !== nowType || nowType === 'han') {
                /* 新的开始 */
                if (word && prevType && !blockList.test(word)) {
                    if (map[word]) {
                        map[word]++;
                    } else {
                        map[word] = 1;
                    }
                }

                word = char;
                prevType = nowType;
            } else {
                word += char;
            }
        }

        return map;
    };

    var beyondMap = function (mapList) {
        var map = {};
        for (var i = 0; i < mapList.length; i++) {
            for (var j in mapList[i]) {
                if (!map[j]) {
                    map[j] = new Array(mapList.length).fill(0);
                }

                map[j][i]++;
            }
        }

        return map;
    };

    var cos = function (map) {
        var deno1 = 0, deno2 = 0, nume = 0;
        for (var i in map) {
            var sub1 = map[i][0], sub2 = map[i][1];
            deno1 += sub1 * sub1;
            deno2 += sub2 * sub2;
            nume  += sub1 * sub2;
        }

        return nume / (Math.sqrt(deno1) * Math.sqrt(deno2));
    };

    var beyond = function (text1, text2) {
        return cos(beyondMap([
            splitText(text1),
            splitText(text2)
        ]));
    };
    
}());

// 调用比较两个文本
compare("text1", 'text2');