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VUE-计算属性

2017-12-27 23:55 537 查看
computed/methods两种方式的最终结果确实是完全相同的。然而,不同的是计算属性是基于它们的依赖进行缓存的。计算属性只有在它的相关依赖发生改变时才会重新求值。这就意味着只要
message
还没有发生改变,多次访问
reversedMessage
计算属性会立即返回之前的计算结果,而不必再次执行函数。

computed/methods

<!-- 计算属性computed/methods -->

<div style="height: 250px;background: #CCC;margin: 5px;">

<div style="font-size: 20px;">

v0.计算属性computed/methods</div>

<hr />

<div>

<div>

<p>{{msg}}</p>

</div>

<div>

<p>反转字符串:{{reverseMsg}}</p>

</div>

<div>

<p>反转字符串:{{reverseMsg1()}}</p>

</div>

<div>

<p>Setter/Getter:{{fullName}}</p>

</div>

</div>

</div>

<!-- 计算属性computed/methods -->

<script>

var vm = new Vue({

el: "#appVue",

data: {

msg: "ABCDEFG",

msg1: "abcdefg",

chPart: "Key",

digPart: "123456",

},

computed: {

reverseMsg: function() {

return this.msg.split('').reverse().join('')

},

fullName: {

get: function() {

return this.chPart + this.digPart;

},

set: function(newVar) {

this.chPart = newVar;

this.digPart = newVar;

}

}

},

methods: {

reverseMsg1: function() {

return this.msg1.split('').reverse().join('')

}

}

})

console.log(vm.reverseMsg);

vm.msg = "AAABBB";

console.log(vm.reverseMsg);

vm.fullName = "Null";

</script>

<!DOCTYPE html>
<html style="height: 100%;">

<head>
<meta charset="UTF-8">
<script type="text/javascript" src="../lib/vue.v2.5.12.js"></script>
<title>v-xxx</title>
</head>

<body style="height: 100%;">
<style>
.style0 {
font-size: 25px;
color: green;
}

.style1 {
background: gold;
}
</style>
<!--
VUE-计算属性

REF: http://www.runoob.com/vue2/vue-computed.html https://cn.vuejs.org/v2/guide/computed.html
-->
<div id="appVue">
<!-- 计算属性computed/methods -->
<div style="height: 250px;background: #CCC;margin: 5px;">
<div style="font-size: 20px;">
v0.计算属性computed/methods</div>
<hr />
<div>
<div>
<p>{{msg}}</p>
</div>
<div>
<p>反转字符串:{{reverseMsg}}</p>
</div>
<div>
<p>反转字符串:{{reverseMsg1()}}</p>
</div>
<div>
<p>Setter/Getter:{{fullName}}</p>
</div>
</div>
</div>
</div>
<script>
var vm = new Vue({
el: "#appVue",
data: {
msg: "ABCDEFG",
msg1: "abcdefg",
chPart: "Key",
digPart: "123456",
},
computed: {
reverseMsg: function() {
return this.msg.split('').reverse().join('')
},
fullName: {
get: function() {
return this.chPart + this.digPart;
},
set: function(newVar) {
this.chPart = newVar;
this.digPart = newVar;
}
}
},
methods: {
reverseMsg1: function() {
return this.msg1.split('').reverse().join('')
}
}
})
console.log(vm.reverseMsg);
vm.msg = "AAABBB";
console.log(vm.reverseMsg);
vm.fullName = "Null";
</script>
</body>

</html>


View Code

REF:
http://www.runoob.com/vue2/vue-computed.html https://cn.vuejs.org/v2/guide/computed.html
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