How to solve the problem that vue's setting data data is not updated

With the continuous development of front-end technology, Vue.js has become the preferred framework for many front-end engineers. However, in the process of using Vue.js, sometimes you encounter the problem that Vue's setting data is not updated. This article will analyze this problem and provide solutions.

1. Specific description of the problem

In Vue.js, we can use data to store the state data of the component. Normally, we can get or set the data in data through this.$data.xxx. After modifying the value of data, Vue.js will automatically re-render the page to display the latest data. But sometimes, we will find that the value in the data has been changed, but it is not displayed on the page. The common reasons are as follows.

1. Incompatible data types

The data types in Vue.js are very strict. If the data types are incompatible, the data will not be updated. For example, if you define a variable as a string type, but you assign a numeric type value to it, then it will not be updated.

2. Limitations of the responsive mechanism of Vue.js

The responsive mechanism of Vue.js is implemented based on the Proxy of ES6. When we get or set the data in data through this.$data.xx, Vue.js will automatically call the get and set methods of Proxy to realize the function of monitoring data changes. However, due to Proxy compatibility issues, some browsers may not support it, which leads to data update failure.

3. Asynchronous operations affect data update

In Vue.js, data update is a synchronous process. But sometimes, we may perform some asynchronous operations before the data is updated. If these asynchronous operations are not handled correctly, the data may not be updated.

2. Solution

1. Check the data type

In order to avoid data type incompatibility problems, it is recommended to clearly specify the type when defining a variable. When modifying variable values, try to ensure that the data types are consistent.

2. Solving the responsive mechanism limitations of Vue.js

We can solve the responsive mechanism limitations of Vue.js in the following ways.

(1) Use the forceUpdate method of Vue.js to re-render the component.

For example, there is a data in a component:

data() {
return {

message: 'Hello, Vue!',

};
},

If you modify the message value in the code, but the page is not updated, you can force the page to re-render through the following code:

this.$forceUpdate();

(2) Use Vue.set or this.$set method to update the value of data.

Vue.set is an API provided by Vue.js, which can be used to add a property to a responsive object.

For example, we have the following data:

data() {
return {

person: {
  name: 'Tom',
  age: 18,
},

};
},

If You modified a property of the person object in the code, but the page is not updated. You can update it through the following code:

Vue.set(this.person, 'name', 'Jerry') ;

Or use this.$set method to update:

this.$set(this.person, 'name', 'Jerry');

(3) Monitor data changes in the watch option

Vue.js provides the watch option, which can be used to monitor data changes.

For example, we have the following data:

data() {
return {

message: 'Hello, Vue!',

};
},

If If you want to perform some operations when the value of message changes, you can do so through the following code:

watch: {
message(newVal) {

console.log(newVal);

},
} ,

3. Solve the problem of asynchronous operation affecting data update

If the asynchronous operation is performed before the data is updated, you can use the $nextTick method provided by Vue.js to solve the problem. The $nextTick method will execute the callback function after the next DOM update cycle, so it can ensure that the asynchronous operation is performed after the data update is completed.

For example, we have the following data:

data() {
return {

message: 'Hello, Vue!',

};
},

If If you want to perform an asynchronous operation after modifying the value of the message, you can do so through the following code:

this.message = 'Hello, World!';
this.$nextTick(() => {
//Perform asynchronous operations after DOM update
console.log('Asynchronous operation completed');
});

3. Summary

In Vue In .js, if there is a problem that the data is not updated, it can be solved by the following methods: check whether the data types are consistent; use the forceUpdate, Vue.set or this.$set method provided by Vue.js to update the data; in watch Listen to data changes in the options; use the $nextTick method provided by Vue.js to resolve conflicts between data updates and asynchronous operations. Through the above method, you can solve the problem of vue's setting data not being updated.

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