[Organization and Sharing] 8 Practical Vue Development Tips

This article compiles and shares 8 great Vue development skills, including routing parameter decoupling, functional components, style scope, advanced use of watch, watch monitoring multiple variables, etc. I hope it will be helpful to everyone!

1. Routing parameter decoupling

Usually routing parameters are used in components, most people Will do the following things.

export default {
    methods: {
        getParamsId() {
            return this.$route.params.id
        }
    }
}

Using $route in a component results in a strong coupling to its corresponding route, limiting the flexibility of the component by restricting it to certain URLs. The correct approach is to decouple it through props.

const router = new VueRouter({
    routes: [{
        path:  /user/:id ,
        component: User,
        props: true
    }]
})

After setting the props attribute of the route to true, the component can receive params parameters through props inside the component. [Related recommendations: vuejs video tutorial, web front-end development]

export default {
    props: [ id ],
    methods: {
        getParamsId() {
            return this.id
        }
    }
}

You can also return props through functional mode.

const router = new VueRouter({
    routes: [{
        path:  /user/:id ,
        component: User,
        props: (route) => ({
            id: route.query.id
        })
    }]
})

2. Functional component

Functional component is stateless, it cannot be instantiated, and it does not have any life cycle or methods. Creating functional components is also as simple as adding a functional declaration to your template. It is generally suitable for components that only rely on external data changes, and improves rendering performance due to its lightweight. Everything the component needs is passed through context parameters. It is a context object, see the documentation for specific properties. props here is an object containing all bound properties.

<template functional>
    <div class="list">
        <div class="item" v-for="item in props.list" :key="item.id" @click="props.itemClick(item)">
            <p>{{item.title}}</p>
            <p>{{item.content}}</p>
        </div>
    </div>
</template>

Parent component usage

<template>
    <div>
        <List :list="list" :itemClick="item => (currentItem = item)" />
    </div>
</template>

import List from  @/components/List.vue
export default {
    components: {
        List
    },
    data() {
        return {
            list: [{
                title:  title ,
                content:  content
            }],
            currentItem:
        }
    }
}

3. Style scope

It is common to modify the style of third-party components during development, but Due to the style isolation of scoped attributes, you may need to remove scoped or create a new style. These practices have side effects (component style pollution, lack of elegance), and are implemented using style penetration in the CSS preprocessor. We can use>>> or /deep/ to solve this problem:

<style scoped>
Outer layer >>> .el-checkbox {
  display: block;
  font-size: 26px;

  .el-checkbox__label {
    font-size: 16px;
  }
}
</style>

<style scoped>
/deep/ .el-checkbox {
  display: block;
  font-size: 26px;

  .el-checkbox__label {
    font-size: 16px;
  }
}
</style>

4. Advanced use of watch

watch Triggered when the listener property changes. Sometimes we want the watch to be executed immediately after the component is created. One way that might come to mind is to call it once during the creation lifecycle, but that's not an elegant way to write it, so maybe we could use something like this.

export default {
    data() {
        return {
            name:  Joe
        }
    },
    watch: {
        name: {
            handler:  sayName ,
            immediate: true
        }
    },
    methods: {
        sayName() {
            console.log(this.name)
        }
    }
}

Deep Listening

When listening to an object, when the properties inside the object change, watch will not be triggered, so We can set up deep monitoring for it.

export default {
    data: {
        studen: {
            name:  Joe ,
            skill: {
                run: {
                    speed:  fast
                }
            }
        }
    },
    watch: {
        studen: {
            handler:  sayName ,
            deep: true
        }
    },
    methods: {
        sayName() {
            console.log(this.studen)
        }
    }
}

Trigger the listener to execute multiple methods

Using arrays, you can set multiple forms, including strings, functions, and objects.

export default {
    data: {
        name:  Joe
    },
    watch: {
        name: [
             sayName1 ,
            function(newVal, oldVal) {
                this.sayName2()
            },
            {
                handler:  sayName3 ,
                immaediate: true
            }
        ]
    },
    methods: {
        sayName1() {
            console.log( sayName1==> , this.name)
        },
        sayName2() {
            console.log( sayName2==> , this.name)
        },
        sayName3() {
            console.log( sayName3==> , this.name)
        }
    }
}

5.watch monitors multiple variables

watch itself cannot monitor multiple variables. However, we can "listen to multiple variables" by returning an object with a computed property and then listening to that object.

export default {
    data() {
        return {
            msg1:  apple ,
            msg2:  banana
        }
    },
    compouted: {
        msgObj() {
            const { msg1, msg2 } = this
            return {
                msg1,
                msg2
            }
        }
    },
    watch: {
        msgObj: {
            handler(newVal, oldVal) {
                if (newVal.msg1 != oldVal.msg1) {
                    console.log( msg1 is change )
                }
                if (newVal.msg2 != oldVal.msg2) {
                    console.log( msg2 is change )
                }
            },
            deep: true
        }
    }
}

6. Event parameter $event

$event is a special variable of the event object, which provides us with More parameters are available to implement complex functions. Native Events: Behaves the same as the default event object in Native Events.

<template>
    <div>
        <input type="text" @input="inputHandler( hello , $event)" />
    </div>
</template>

export default {
    methods: {
        inputHandler(msg, e) {
            console.log(e.target.value)
        }
    }
}

Custom event: In the custom event, it is expressed as capturing the value thrown from the child component.

export default {
    methods: {
        customEvent() {
            this.$emit( custom-event ,  some value )
        }
    }
}

<template>
    <div>
        <my-item v-for="(item, index) in list" @custom-event="customEvent(index, $event)">
            </my-list>
    </div>
</template>

export default {
    methods: {
        customEvent(index, e) {
            console.log(e) //  some value
        }
    }
}

7. Programmed event listener

For example, define a timer when the page is mounted and needs to be cleared when the page is destroyed timer. This doesn't seem to be a problem. But looking closer, the only purpose of this.timer is to be able to get the timer number in beforeDestroy, otherwise it is useless.

export default {
    mounted() {
        this.timer = setInterval(() => {
            console.log(Date.now())
        }, 1000)
    },
    beforeDestroy() {
        clearInterval(this.timer)
    }
}

It is best to only access lifecycle hooks if possible. This is not a serious problem but can be considered confusing. We can solve this problem by using or once to listen for page life cycle destruction:

export default {
    mounted() {
        this.creatInterval( hello )
        this.creatInterval( world )
    },
    creatInterval(msg) {
        let timer = setInterval(() => {
            console.log(msg)
        }, 1000)
        this.$once( hook:beforeDestroy , function() {
            clearInterval(timer)
        })
    }
}

使用这种方法，即使我们同时创建多个定时器，也不影响效果。这是因为它们将在页面被销毁后以编程方式自动清除。8.监听组件生命周期通常我们使用 $emit 监听组件生命周期，父组件接收事件进行通知。

子组件

export default {
    mounted() {
        this.$emit( listenMounted )
    }
}

父组件

<template>
    <div>
        <List @listenMounted="listenMounted" />
    </div>
</template>

其实有一种简单的方法就是使用@hook 来监听组件的生命周期，而不需要在组件内部做任何改动。同样，创建、更新等也可以使用这个方法。

<template>
    <List @hook:mounted="listenMounted" />
</template>

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