demo.js

// 定义一个myVue构造函数 充当Vue的实例对象
function myVue(opt) {
    console.log(this);
    // 给一个初始化构造函数的方法
    this._init(opt);
}

// 在原型上增加init方法
myVue.prototype._init = function (opt) {
    this.$option = opt;
    this.$el = document.querySelector(opt.el);
    this.$data = opt.data;
    this.$methods = opt.methods;

    this._binding = {};
    this._obverse(this.$data);
    this._complie(this.$el);
}

// 建立_obverse 处理data
myVue.prototype._obverse = function (obj) {
    var _this = this;
    Object.keys(obj).forEach(function (key) {
        if (obj.hasOwnProperty(key)) {
            _this._binding[key] = {
                _directives: []
            };
            console.log(_this._binding[key])
            var value = obj[key];
            if (typeof value === 'object') {
                _this._obverse(value);
            }
            var binding = _this._binding[key];
            Object.defineProperty(_this.$data, key, {
                enumerable: true,
                configurable: true,
                get: function () {
                    console.log(`${key}获取${value}`);
                    return value;
                },
                set: function (newVal) {
                    console.log(`${key}更新${newVal}`);
                    if (value !== newVal) {
                        value = newVal;
                        binding._directives.forEach(function (item) {
                            item.update();
                        })
                    }
                }
            })
        }
    })
}

// myVue.prototype._obverse = function (obj) {
//     var _this = this;

//     var value;
//     for (var key in obj) {
//         if (obj.hasOwnProperty(key)) {
//             this._binding[key] = {
//                 _directives: []
//             };

//             var binding = this._binding[key];

//             value = obj[key];
//             if (typeof value === "object") {
//                 this._obverse(value);
//             }
//             Object.defineProperty(this.$data, key, {
//                 enumerable: true,
//                 configurable: true,
//                 getter: function () {
//                     console.log(`获取${value}`);
//                 },
//                 setter: function (newVal) {
//                     console.log(`更新${newVal}`);
//                     if (value !== newVal) {
//                         value = newVal;
//                         binding._directives.forEach((item) => {
//                             item.update();
//                         });
//                     }
//                 }
//             })
//         }
//     }

// }


myVue.prototype._complie = function (root) { // root 为id为app的Element元素，也就是我们的根元素
    var _this = this;
    console.log(root);
    var nodes = root.children;
    for (var i = 0; i < nodes.length; i++) {
        var node = nodes[i];
        if (node.children.length) {
            this._complie(node);
        }

        if (node.hasAttribute('v-click')) {
            node.onclick = (function () {
                var attrVal = nodes[i].getAttribute('v-click');
                return _this.$methods[attrVal].bind(_this.$data);
            })();
        }

        if (node.hasAttribute('v-model') && (node.tagName = 'INPUT' || node.tagName == 'TEXTAREA')) {
            node.addEventListener('input', (function (key) {
                var attrVal = node.getAttribute('v-model');
                _this._binding[attrVal]._directives.push(new Watcher(
                    'input',
                    node,
                    _this,
                    attrVal,
                    'value'
                ))

                return function () {
                    _this.$data[attrVal] = nodes[key].value;
                }
            })(i));
        }

        if (node.hasAttribute('v-bind')) {
            var attrVal = node.getAttribute('v-bind');
            _this._binding[attrVal]._directives.push(new Watcher(
                'text',
                node,
                _this,
                attrVal,
                'innerHTML'
            ))
        }
    }
}


// 建立一个指令类 用来绑定更新函数
function Watcher(name, el, vm, exp, attr) {
    this.name = name; //指令名称，例如文本节点，该值设为"text"
    this.el = el; //指令对应的DOM元素
    this.vm = vm; //指令所属myVue实例
    this.exp = exp; //指令对应的值，本例如"number"
    this.attr = attr; //绑定的属性值，本例为"innerHTML"

    this.update()
}

Watcher.prototype.update = function () {
    this.el[this.attr] = this.vm.$data[this.exp]; //比如 H3.innerHTML = this.data.number; 当number改变时，会触发这个update函数，保证对应的DOM内容进行了更新。
}


window.onload = function () {
    var app = new myVue({
        el: "#app",
        data: {
            number: 0,
            count: 0,

        },
        methods: {
            increment: function () {
                this.number++;
            },
            incre: function () {
                this.count++;
            }
        }
    });
}