Vue学习笔记(十九)——组件props信息的修改
组件props信息的修改
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本文主要介绍一下组件对props(即传入参数)的处理。
props是父组件给子组件传递的参数,而子组件需要修改props的场景非常多,但props并不像组件自己的属性那样可以随意修改(因为props会同时影响父组件和子组件),props的修改必须遵循以下规则:
- 子组件不能直接修改props;
- 如果props是对象,子组件可以修改对象的属性值(包括增加删除属性);
- 如果props是数组,子组件可以修改数组的元素(包括增加删除元素),如果元素是对象,还可以修改元素的属性值(包括增加删除元素属性)。
下面上示例代码:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>props</title>
<script src="https://cdn.bootcss.com/vue/2.6.10/vue.js"></script>
</head>
<body>
<div id="app">
<div>
<button type="button" @click="show">container</button>
</div>
<container :parama="paramA" :paramb="paramB" :paramc="paramC" :paramd="paramD"></container>
</div>
<script>
Vue.component('container', {
template: '<div><br><button type="button" @click="changeA">change paramA</button>' +
'<br><br><button type="button" @click="changeB">change paramB</button>' +
'<br><br><button type="button" @click="changeC">change paramC</button>' +
'<br><br><button type="button" @click="changeD">change paramD</button></div>',
props: ["parama", "paramb", "paramc", "paramd"],
methods: {
changeA: function () {
//触发时会报错
this.parama = "paramA changed";
},
changeB: function () {
this.paramb.key = "key changed";
this.paramb.value = "value changed";
//上下两种写法是等价的
// this.$set(this.paramb, "key", "key changed");
// this.$set(this.paramb, "value", "value changed");
this.paramb.add = "new attr";
delete this.paramb.removeAttr;
},
changeC: function () {
this.paramc.push(4);
this.paramc[0] = -1;
//上下两种写法是等价的
// this.$set(this.paramc, 0, -1);
},
changeD: function () {
this.paramd.push({
lon: 40,
lat: 70
});
this.paramd[0] = {
lon: 20,
lat: 50
};
//上下两种写法是等价的
// this.$set(this.paramd, 0, {
// lon: 20,
// lat: 50
// });
}
}
});
new Vue({
el: '#app',
data: {
paramA: "paramA",
paramB: {
key: "it is key",
value: "it is value",
removeAttr: "it is remove"
},
paramC: [1, 2, 3],
paramD: [
{
lon: 30,
lat: 60
}
]
},
methods: {
show: function () {
console.log("paramA is " + this.paramA);
console.log("paramB.key is " + this.paramB.key);
console.log("paramB.value is " + this.paramB.value);
if (this.paramB.add) {
console.log("paramB.add is " + this.paramB.add);
}
if (this.paramB.removeAttr) {
console.log("paramB.removeAttr is " + this.paramB.removeAttr);
}
console.log("paramC.length is " + this.paramC.length);
console.log("paramC[0] is " + this.paramC[0]);
console.log("paramD.length is " + this.paramD.length);
console.log("paramD[0].lon is " + this.paramD[0].lon);
console.log("paramD[0].lat is " + this.paramD[0].lat);
if (this.paramD.length === 2) {
console.log("paramD[1].lon is " + this.paramD[1].lon);
console.log("paramD[1].lat is " + this.paramD[1].lat);
}
}
}
});
</script>
</body>
</html>
当尝试直接修改props时(对应上例为点击"change paramA"按钮),控制台会报错:
当执行其他修改动作时(对应上例为点击除"change paramA"外的其他按钮),控制台没有报错,然后在父组件中查看props是否成功修改(点击"container"按钮),可以看到父组件传入的props都修改成功了:
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