The content of this article is about the design process (code) of the Vue.js component library event system. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.
Let’s take input-number as an example:
@ is the abbreviation of v-on instruction, used to bind event listeners:
<InputNumber @on-change="change" :max="10" :min="1" v-model="value1"> </InputNumber>
When we use components, A custom
event will be registered:
methods: { change (v) { console.log(v) } }
The way to trigger it inside the component is also very simple:
calls$emit
to trigger the current instance event, the event name is on-change
this.$emit('on-change', val);
Here comes the idea, if the outer layer of InputNumber
is nested in a certain FormItem
component, The mutual calls between events are also similar, but there is an additional assumption:
Like element
and iview
More designs A mixins
, which provides a method: dispatch
It accepts 3
parameters:
componentName Component name
eventName Custom event name
params Parameters passed by the event
dispatch(componentName, eventName, params) { }
For example, similar to input-number
, many of the components embedded in this form will be designed to interact with FormItem
:
this.dispatch('FormItem', 'on-form-change', val);
We are designing FormItem
When using components, note:
export default { name: 'FormItem' }
Then register a custom event in the same way:
<Form-item @on-form-change="test"> </Form-item>
Let’s take a look at the inside of the dispatch function:
The idea is to look up the parent element layer by layer:
var parent = this.$parent || this.$root;
var name = parent.$options.name;
while (parent && (!name || name !== componentName)) { // ... }
input-number Dispatch is called internally and the parameters are passed in, which is to keep looking for the parent element
name which is
FormItem. Inside the while:
parent = parent.$parent; if (parent) { name = parent.$options.name; }
if (parent) { parent.$emit.apply(parent, [eventName].concat(params)); }
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