wx app require implementation

require.js

var dir = function (e) {
        var t = e.match(/(.*)\/([^\/]+)?$/);
        // 默认相对于当前目录
        return t && t[1] ? t[1] : "./"
    },
        // the inner require path is relative to the base directory of the requiring file.
        _require = function (path) {
            var baseDir = dir(path);
            return function (e) {
                if ("string" != typeof e) throw new Error("require args must be a string");
                for (var normalizedParts = [], parts = (baseDir + "/" + e).split("/"), i = 0, len = parts.length; i < len; ++i) {
                    var part = parts[i];
                    if ("" != part && "." != part)
                        if (".." == part) {
                            if (0 == normalizedParts.length) throw new Error("can't find module : " + e);
                            normalizedParts.pop()
                        } else i + 1 < len && ".." == parts[i + 1] ? i++ : normalizedParts.push(part)
                }
                try {
                    var noramlizedPath = normalizedParts.join("/");
                    return /\.js$/.test(noramlizedPath) || (noramlizedPath += ".js"), require(noramlizedPath)
                } catch (e) {
                    throw e
                }
            }
        };
    require = function (path) {
        if ("string" != typeof path) throw new Error("require args must be a string");
        // all module paths are relative to project root
        var i = modules[path];
        if (!i) throw new Error('module "' + path + '" is not defined');
        if (i.status === e) {
            var factory = i.factory,
                module = {
                    exports: {}
                },
                undef = void 0;
            factory && (undef = factory(_require(path), module, module.exports)), i.exports = module.exports || undef, i.status = t
        }
        return i.exports
    }