computed \ methods 里边是（各种）函数，函数里边调用变量用this.
computed 里边是 （各种）函数返回对象
实例中data是对象, 在组件中（在其他里边）data是函数返回对象
push() 方法可向数组的末尾添加一个或多个元素，并返回新的长度。
v-model:把当前这个input里边的值指到哪里
<input v-model="current.title" id="task-input" type="text">
JSON.stringify() 方法将 javascript对象 转换为 JSON字符串。
JSON.parse() 方法将 JSON字符串 转换为 JavaScript对象。
<p id="demo"></p>
<script>
var obj = { "name":"runoob", "alexa":10000, "site":"www.runoob.com"};
var myJSON = JSON.stringify(obj);
document.getElementById("demo").innerhtml = myJSON;
</script>
//运行结果：{"name":"runoob","alexa":10000,"site":"www.runoob.com"}
<p id="demo"></p>
<script>
var text = ‘{"employees":[‘ +
‘{"name":"菜鸟教程","site":"http://www.runoob.com" },‘ +
‘{"name":"Google","site":"http://www.Google.com" },‘ +
‘{"name":"Taobao","site":"http://www.taobao.com" }]}‘;
obj = JSON.parse(text);
document.getElementById("demo").innerHTML = obj;
</script>
//运行结果：[object Object]
<p id="demo"></p>
<script>
var text = ‘{"employees":[‘ +
‘{"name":"菜鸟教程","site":"http://www.runoob.com" },‘ +
‘{"name":"Google","site":"http://www.Google.com" },‘ +
‘{"name":"Taobao","site":"http://www.taobao.com" }]}‘;
obj = JSON.parse(text);
document.getElementById("demo").innerHTML =
obj.employees[1].name;
</script>
//运行结果：Google
<p id="demo"></p>
<script>
var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};
document.getElementById("demo").innerHTML = person;
</script>
//运行结果：[object Object]
<p id="demo"></p>
<script>
var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};
document.getElementById("demo").innerHTML = person.firstName;
</script>
//运行结果：John