Vue.js之生命周期

2018-11-20 03:16:29来源:博客园 阅读 ()

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有时候,我们需要在实例创建过程中进行一些初始化的工作,以帮助我们完成项目中更复杂更丰富的需求开发,针对这样的需求,Vue提供给我们一系列的钩子函数。

vue生命周期

beforeCreate

在实例初始化之后,数据观测 (data observer) 和 event/watcher 事件配置之前被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            });
    </script>

</body>
</html>

效果:

created

在实例创建完成后被立即调用。在这一步,实例已完成以下的配置:数据观测 (data observer),属性和方法的运算,watch/event 事件回调。然而,挂载阶段还没开始,$el 属性目前不可见。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="static/vue.min.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            created() {
                console.group("Created");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        })
    </script>

</body>
</html>

beforeMount

在挂载开始之前被调用:相关的 render 函数首次被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            created() {
                console.group("Created");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeMount() {
                console.group("beforeMount");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        })
    </script>

</body>
</html>

mounted

el 被新创建的 vm.$el 替换,并挂载到实例上去之后调用该钩子。如果 root 实例挂载了一个文档内元素,当 mounted 被调用时 vm.$el 也在文档内。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            created() {
                console.group("Created");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeMount() {
                console.group("beforeMount");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            mounted() {
                console.group("mounted");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
        })
    </script>

</body>
</html>

beforeUpdate

数据更新时调用,发生在虚拟 DOM 打补丁之前。这里适合在更新之前访问现有的 DOM,比如手动移除已添加的事件监听器。

该钩子在服务器端渲染期间不被调用,因为只有初次渲染会在服务端进行.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            created() {
                console.group("Created");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeMount() {
                console.group("beforeMount");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            mounted() {
                console.group("mounted");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeUpdate() {
                console.group("beforeUpdate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        })
    </script>

</body>
</html>

updated

由于数据更改导致的虚拟 DOM 重新渲染和打补丁,在这之后会调用该钩子。

当这个钩子被调用时,组件 DOM 已经更新,所以你现在可以执行依赖于 DOM 的操作。然而在大多数情况下,你应该避免在此期间更改状态。如果要相应状态改变,通常最好使用计算属性或 watcher 取而代之。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        {{ name }}
        <button @click="myClick">点击修改数据</button>
    </div>

    <script>

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            data: {
                name: "Alex"
            },
            methods: {
                init: function () {
                    console.log(this.name);
                },
                myClick: function () {
                    this.name = "Pizza";
                }
            },
            beforeCreate() {
                console.group("beforeCreate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            created() {
                console.group("Created");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeMount() {
                console.group("beforeMount");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            mounted() {
                console.group("mounted");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            beforeUpdate() {
                console.group("beforeUpdate");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
            updated() {
                console.log("updated");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        })
    </script>

</body>
</html>

activated

keep-alive 组件激活时调用。<keep-alive> 包裹动态组件时,会缓存不活动的组件实例,而不是销毁它们

该钩子在服务器端渲染期间不被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.min.js"></script>
</head>
<body>

    <div id="app">
        <App></App>
    </div>

    <script>
        let Laside = {
            template: `
                <div>
                    <h1>{{ message }}</h1>
                    <button @click="changeData">点击修改数据</button>
                </div>
            `,

            data () {
                return {
                    message: "Hello Vue!"
                }
            },

            methods: {
                init: function () {
                    console.log(this.message)
                }
                changeData: function () {
                    this.mes = "Pizza is here!";
                }
            },

            // 组件的创建和销毁对性能有影响
            beforeDestroy () {
                console.log("beforeDestroy");
            },

            destroyed () {
                console.log("destroyed");
            },

            activated () {
                console.group("activated");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("message: ", this.message);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
        };

        let App = {
            template: `
                <div >
                    <keep-alive>
                        <Laside v-if="isShow"></Laside>
                    </keep-alive>
                    <button @click="showHide">创建消除组件</button>
                </div>
            `,
            components: {
                "Laside": Laside,
            },
            methods: {
                showHide: function () {
                    this.isShow = !this.isShow;
                }
            },
            data () {
                return {
                    isShow: true,
                }
            }
        };

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            components: {
                App,
            }
        })
    </script>

</body>
</html>

deactivated

keep-alive 组件停用时调用。

该钩子在服务器端渲染期间不被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.min.js"></script>
</head>
<body>

    <div id="app">
        <App></App>
    </div>

    <script>
        let Laside = {
            template: `
                <div>
                    <h1>{{ mes }}</h1>
                    <button @click="changeData">点击修改数据</button>
                </div>
            `,

            data () {
                return {
                    message: "Hello Vue!"
                }
            },

            methods: {
                init: function () {
                    console.log(this.message);
                }
                changeData: function () {
                    this.mes = "Pizza is here!";
                }
            },

            // 组件的创建和销毁对性能有影响
            beforeDestroy () {
                console.log("beforeDestroy");
            },

            destroyed () {
                console.log("destroyed");
            },

            activated () {
                console.group("activated");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("message: ", this.message);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },

            deactivated () {
                console.group("deactivated");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        };

        let App = {
            template: `
                <div >
                    <keep-alive>
                        <Laside v-if="isShow"></Laside>
                    </keep-alive>
                    <button @click="showHide">创建消除组件</button>
                </div>
            `,
            components: {
                "Laside": Laside,
            },
            methods: {
                showHide: function () {
                    this.isShow = !this.isShow;
                }
            },
            data () {
                return {
                    isShow: true,
                }
            }
        };

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            components: {
                App,
            }
        })
    </script>

</body>
</html>

beforeDestroy

实例销毁之前调用。在这一步,实例仍然完全可用。频繁的创建和销毁组件对性能的影响很大,因此可以使用activated和deactivated。

该钩子在服务器端渲染期间不被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.js"></script>
</head>
<body>

    <div id="app">
        <App></App>
    </div>

    <script>
        let Laside = {
            template: `
                <div>
                    <h1>{{ mes }}</h1>
                    <button @click="changeData">点击修改数据</button>
                </div>
            `,

            data () {
                return {
                    mes: "Hello Vue!"
                }
            },

            methods: {
                changeData: function () {
                    this.mes = "Pizza is here!";
                }
            },

            // 组件的创建和销毁对性能有影响
            beforeDestroy() {
                console.log("beforeDestroy");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerText: ", document.getElementById("app").innerText);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },
        };

        let App = {
            template: `
                <div >
                    <Laside v-if="isShow"></Laside>
                    <button @click="showHide">创建消除组件</button>
                </div>
            `,
            components: {
                "Laside": Laside,
            },
            methods: {
                showHide: function () {
                    this.isShow = !this.isShow;
                }
            },
            data () {
                return {
                    isShow: true,
                }
            }
        };

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            components: {
                App,
            }
        })
    </script>

</body>
</html>

destroyed

Vue 实例销毁后调用。调用后,Vue 实例指示的所有东西都会解绑定,所有的事件监听器会被移除,所有的子实例也会被销毁。

该钩子在服务器端渲染期间不被调用。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../statics/vue.min.js"></script>
</head>
<body>

    <div id="app">
        <App></App>
    </div>

    <script>
        let Laside = {
            template: `
                <div>
                    <h1>{{ mes }}</h1>
                    <button @click="changeData">点击修改数据</button>
                </div>
            `,

            data () {
                return {
                    mes: "Hello Vue!"
                }
            },

            methods: {
                changeData: function () {
                    this.mes = "Pizza is here!";
                }
            },

            // 组件的创建和销毁对性能有影响
            beforeDestroy() {
                console.log("beforeDestroy");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            },

            destroyed () {
                console.log("destroyed");
                console.log("el: ", this.$el);
                console.log("data: ", this.$data);
                console.log("name: ", this.name);
                console.log("init: ", this.init);
                console.log("innerHTML: ", document.getElementById("app").innerHTML);
            }
        };

        let App = {
            template: `
                <div >
                    <Laside v-if="isShow"></Laside>
                    <button @click="showHide">创建消除组件</button>
                </div>
            `,
            components: {
                "Laside": Laside,
            },
            methods: {
                showHide: function () {
                    this.isShow = !this.isShow;
                }
            },
            data () {
                return {
                    isShow: true,
                }
            }
        };

        new Vue({
            el: "#app",
            // 在template中使用组件与在body中使用组件是一样的
            // template: `<cont></cont>`,
            components: {
                App,
            }
        })
    </script>

</body>
</html>

 

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