Analysis of changes in Vue detection objects and arrays

This article shares with you the relevant knowledge points and example codes for Vue to detect changes in objects and arrays. Friends who are interested can refer to it.

In JavaScript, objects and arrays are reference types, pointing to the same memory space. If prop is an object or array, changing it inside the child component will affect the state of the parent component. You can modify objects or arrays directly in subcomponents, but changes will not occur if the data changes.

Detecting object changes

1. Unable to detect the addition or deletion of object attributes

var vm = new Vue({
 data:{
   data111:{
     a = 1
   }
 }
})

data111.a = 2;//This can cause changes

But data111.b = 2; and vm.b = 2 cannot detect changes

Required Use

Vue.set(object, key, value)

such as

$set(data111, b, 2);

or:

$set(key,value)

such as

vm.$set(‘b', 2)；

to detect the array Change

Changes cannot be detected in the following two situations:

1. Set the element directly through the index, such as arr[0]=12;

2. Directly modify the length of the array, such as vm.arr.length

Vue.set( object, key, value )

Usage:

this.$set(this.arr,0,12)

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