Detailed example of how to modify props in the vue render function

Vue's render function is a very powerful tool that can help us create components and render pages more freely. In some scenarios, the render function can also help us improve some performance. In some cases, we want to modify props in the render function, so how to do it? Let’s take a look below.

Before we officially start discussing how to modify the props in the render function, we need to make it clear: props are read-only. This means that we cannot directly modify the values ​​of props inside the component, otherwise an error will be reported. So how do we modify props in the render function? Vue provides us with a solution, which is to use function parameters to modify props values.

The following is an example to demonstrate how to modify props in the render function:

Vue.component('my-component', {
  props: ['myText'],
  render(h, context) {
    // 利用函数参数对props值进行修改
    context.props.myText = '这是修改后的文本';

    return h('div', {}, this.myText);
  }
})

In the above code, we define a component my-component, which has A props attribute myText. In the render function, we can use the function parameter context to manipulate the props value, so that we can modify the props value in the component.

It should be noted that in the above code, we modified the props attribute value of context, but did not directly modify the props in this. In this case, even if It is a modified props value and will not be updated inside the component. The reading and rendering of props are performed through the props attribute of the context. Therefore, when modifying props, you need to use the props attribute of the context.

In addition, it should be noted that when modifying props, we need to ensure that the parameters used are defined in props. Otherwise, an error will be reported. For example, in the following code, try to modify a property that has not been defined in props:

Vue.component('my-component', {
  props: ['myText'],
  render(h, context) {
    // 尝试修改一个没有在props中定义过的属性
    context.props.myWrongText = '这是一个错误的文本';

    return h('div', {}, this.myText);
  }
})

When executing the above code, the console will report an error: "[Vue warn ]: Unknown custom element: - did you register the component correctly? For recursive components, make sure to provide the "name" option.". Therefore, when modifying props, you need to pay attention to the properties defined in props.

In addition to the above methods, when modifying props, we can also achieve it through set and Object.defineProperty. However, it should be noted that these methods may have some impact on rendering performance and component behavior, so they need to be used with caution.

Summary: In Vue's render function, using function parameters to modify props is a relatively simple and common method. It should be noted that when modifying props, you must modify the properties defined in props. You also need to pay attention to the possible impact on performance and behavior, and use other methods with caution.

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