简单模拟vue数据绑定（low版本👎）

<span id='spanName'></span><br />
<input type='text' id='inputName'/>

let obj = {
    name: ''
}

// 2.0 方式
Object.defineProperty(obj,'name',{
    get() {
        return this.value;
    },
    set(val) {
        this.value = val;
        observer();

    }
});

// 3.0 方式
obj = new Proxy(obj, {
    get(target, prop) {
        return target[prop];
    },
    set(target, prop, value) {
        target[prop] = value;
        observer();
    }
})
function observer() {
    spanName.innerHTML = obj.name;
    inputName.value = obj.name;
}
inputName.oninput = function () {
    obj.name = this.value;
}