1. The form instructions:
v-model = "variable" variable associated with a value
Normal: variable represents the value value
Single-box: a value for a variable value of a plurality of single box
Single box: variable is a Boolean value, whether the check on behalf of
Multi-box: variable is an array, storing the selected value option
2. conditional instructions:
v-show = '' Boolean variable ": hidden when using {display: none} use when rendering the layout requirements, can make changes.
v-if = '' Boolean variable ": hide, not rendering the page from scratch, there are requirements when using data security
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<title></title>
<style>
[v-cloak] { display: none; }
.box {
width: 200px;
height: 200px;
}
.r {background-color: red}
.b {background-color: blue}
.g {background-color: green}
.active {
background-color: #b1e5ff;
}
</style>
</head>
<body>
<div id="app" v-cloak>
<!--条件指令：
v-show="布尔变量" 隐藏时，采用display:none进行渲染
v-if="布尔变量" 隐藏时，不再页面中渲染(保证不渲染的数据泄露)
-----------------------------
v-if | v-else-if | v-else
-->
<div class="box r" v-show="is_show"></div>
<div class="box b" v-if="is_show"></div>
<hr>
<div class="wrap">
<div>
<button @click="page='r_page'" :class="{active: page === 'r_page'}">红</button>
<button @click="page='b_page'" :class="{active: page === 'b_page'}">蓝</button>
<button @click="page='g_page'" :class="{active: page === 'g_page'}">绿</button>
</div>
<div class="box r" v-if="page === 'r_page'"></div>
<div class="box b" v-else-if="page === 'b_page'"></div>
<div class="box g" v-else></div>
</div>
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
is_show: false,
page: 'r_page'
}
})
</script>
</html>3. loop instruction
v-for="(v,i) in str |arr"
v-for="(v,k,i) in dic"
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<title>todo list 案例</title>
<style>
li:hover {
color: red;
cursor: pointer;
}
</style>
</head>
<body>
<div id="app">
<input type="text" v-model="comment">
<button type="button" @click="send_msg">留言</button>
<ul>
<li v-for="(msg, i) in msgs" @click="delete_msg(i)">{{ msg }}</li>
</ul>
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
comment: '',
msgs: localStorage.msgs ? JSON.parse(localStorage.msgs) : [],
},
methods: {
send_msg() {
// 将comment添加到msgs数组中：unshift push 首尾增 | shift pop 首尾删
// this.msgs.push(this.comment);
// 数组操作最全方法：splice(begin_index, count, ...args)
//begin_index:从第几位开始，操作几位，操作为。。。，args不写默认操作为空，
// 也就是删除，写了就是替换为相应内容。
// this.msgs.splice(0, 2);
if (!this.comment) {
alert('请输入内容');
return false;
}
this.msgs.push(this.comment);
this.comment = '';
localStorage.msgs = JSON.stringify(this.msgs);
},
delete_msg(index) {
this.msgs.splice(index, 1);
localStorage.msgs = JSON.stringify(this.msgs);
}
}
})
</script>
<script>
// 前台数据库
// localStorage: 永久存储
// sessionStorage：临时存储(所属页面标签被关闭后，清空)
// 存
// localStorage.n1 = 10;
// sessionStorage.n2 = 20;
// 取
// console.log(localStorage.n1);
// console.log(sessionStorage.n2);
// 数组等类型需要先序列化成JSON
// localStorage.arr = JSON.stringify([1, 2, 3]);
// console.log(JSON.parse(localStorage.arr));
// 清空数据库
// localStorage.clear();
</script>
</html>4. delimiter:
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div id="app">
{{ msg }}
[{ msg }]
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
msg: 'message'
},
delimiters: ['[{', '}]'], // 修改插值表达式符号，delimiters指定对应的格式才能渲染出来，
// 用不同格式是防止和django前端的表示变量的{{}}冲突
})
</script>
</html>5. Filter:
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<title>过滤器</title>
</head>
<body>
<div id="app">
<!--
总结：
1、在filters成员中定义过滤器方法
2、可以对多个值进行过滤，过滤时还可以额外传入辅助参数
3、过滤的结果可以再进行下一次过滤(过滤的串联)
-->
<p>{{ num | f1 }}</p>
<p>{{ a, b | f2(30, 40) | f3 }}</p>
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
num: 10,
a: 10,
b: 20,
},
filters: {
// 传入所有要过滤的条件，返回值就是过滤的结果
f1 (num) {
console.log(num);
return num * 10;
},
f2 (a, b, c, d) {
console.log(a, b, c, d);
return a + b + c + d;
},
f3 (num) {
return num * num;
}
}
})
</script>
</html>6. Calculate properties:
The method of calculation of computed attribute can be declared properties (Method properties must not be repeated in data declarations)
- The method attribute must render the page, will enable the binding method, binding method is the return value of the method attribute
- All variables that appear in the bound method will be monitored, any occurrence of a variable value updates will re-trigger the binding methods to update the value of the property method
General problem to be solved: a variable value dependent on multiple variables
<body>
<div id="app">
<input type="number" min="0" max="100" v-model="n1">
+
<input type="number" min="0" max="100" v-model="n2">
=
<button>{{ result }}</button>
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
n1: '',
n2: '',
// result: 0,
},
computed: {
result () {
console.log('被调用了');
n1 = +this.n1;
n2 = +this.n2;
return n1 + n2;
}
}
})
</script>7. Monitoring attributes:
<body>
<div id="app">
<p>姓名：<input type="text" v-model="full_name"></p>
<p>姓：{{ first_name }}</p>
<p>名：{{ last_name }}</p>
</div>
</body>
<script src="js/vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
full_name: '',
first_name: '未知',
last_name: '未知',
},
watch: {
// n是监听的属性当前值，o是其上一次的值，监听的属性值每次更新都会回调监听方法
/**
* 总结：
* 1、监听的属性需要在data中声明，监听方法不需要返回值
* 2、监听的方法名就是监听的属性名，该属性值发生更新时就会回调监听方法
* 3、监听方法有两个回调参数：当前值，上一次值
*
* 解决的问题：多个变量值依赖于一个变量值
*/
full_name(n, o) {
name_arr = n.split('');
this.first_name = name_arr[0];
this.last_name = name_arr[1];
},
}
})
</script>