过度和动画

内置组件 Transition

官网详细文档：https://v2.cn.vuejs.org/v2/guide/transitions.html

时机

Transition组件会监控slot中唯一根元素的出现和消失，并会在其出现和消失时应用过渡效果

具体的监听内容是：

  • 它会对新旧两个虚拟节点进行对比（diff），如果旧节点被销毁，则应用消失效果，如果新节点是新增的，则应用进入效果
  • 如果不是上述情况，则它会对比新旧节点，观察其v-show是否变化，true->false应用消失效果，false->true应用进入效果

流程

类名规则：

  1. 如果transition上没有定义name，则类名为v-xxxx
  2. 如果transition上定义了name，则类名为${name}-xxxx
  3. 如果指定了类名，直接使用指定的类名

指定类名见：自定义过渡类名

1. 进入效果

2. 消失效果

过渡组

Transision可以监控其内部的单个 dom 元素的出现和消失，并为其附加样式

如果要监控一个 dom 列表，就需要使用TransitionGroup组件

它会对列表的新增元素应用进入效果，删除元素应用消失效果，对被移动的元素应用v-move样式

被移动的元素之所以能够实现过渡效果，是因为 TransisionGroup 内部使用了 Flip 过渡方案

头像切换效果（也可以做无缝轮播图）

<template>
    <div class="container">
        <div class="btns">
            <button @click="prev">prev</button>
            <button @click="next">next</button>
        </div>
        <transition
            :name="`image-${direction}`"
            enter-active-class="image-enter-active"
            leave-active-class="image-leave-active"
        >
            <img class="image" :src="curImage" :key="curIndex" />
        </transition>
    </div>
</template>

<script>
export default {
    data() {
        return {
            images: [
                "https://10.idqqimg.com/eth/ajNVdqHZLLAJib8odhz8Th2Z4Gat0axooYaxANJlaLEwTomre0hx8Y5yib6FxDZxsgiaYG1W2ETbrU/130?tp=webp",
                "https://10.idqqimg.com/eth/ajNVdqHZLLDqYf0PtFibF9JNOnRbAw7DicWPicmfRkQwPeK2mnZ7ZJzZFdsCwCWdcwhEqoVphXiaDHE/130?tp=webp",
                "https://thirdqq.qlogo.cn/g?b=sdk&k=LaERpMuX1ZjWTQmhrhst6Q&s=100&t=0&tp=webp",
                "https://10.idqqimg.com/eth/ajNVdqHZLLDXIjdTYsqbfkxiaibd3lYGEgfiaEwficYfK2ogZDicCxaKibVibGA2Cj2ltgOvCm1tbRs1iac/130?tp=webp",
                "https://thirdqq.qlogo.cn/g?b=sdk&k=pfIficic6WRliaLULZudVI5Tw&s=640&t=1600139160&tp=webp",
            ],
            curIndex: 0,
            direction: "next",
        };
    },
    computed: {
        curImage() {
            return this.images[this.curIndex];
        },
        maxIndex() {
            return this.images.length - 1;
        },
    },
    methods: {
        next() {
            this.curIndex++;
            if (this.curIndex > this.maxIndex) {
                this.curIndex = 0;
            }
            this.direction = "next";
        },
        prev() {
            this.curIndex--;
            if (this.curIndex < 0) {
                this.curIndex = this.maxIndex;
            }
            this.direction = "prev";
        },
    },
};
</script>

<style>
.container {
    text-align: center;
}
.btns button {
    margin: 1em 0.5em;
}
.image {
    position: absolute;
    top: 100px;
    width: 200px;
    height: 200px;
    border-radius: 50%;
    left: 50%;
    margin-left: -100px;
}
.image-next-enter,
.image-prev-leave-to {
    opacity: 0;
    transform: translateX(200px);
}
.image-next-leave-to,
.image-prev-enter {
    opacity: 0;
    transform: translateX(-200px);
}
.image-enter-active,
.image-leave-active {
    transition: 0.5s;
}
</style>

TransitionGroup demo

<template>
    <div id="app">
        <button @click="addNumber">add number</button>
        <button @click="delNumber">delete number</button>
        <button @click="shuffle">shuffle</button>
        <transition-group name="nums" tag="ul">
            <li v-for="item in nums" :key="item">{{ item }}</li>
        </transition-group>
    </div>
</template>

<script>
export default {
    data() {
        return {
            nums: [1, 2, 3, 4, 5, 6],
            next: 7,
        };
    },
    methods: {
        getRandomIndex() {
            return Math.floor(Math.random() * this.nums.length);
        },
        addNumber() {
            var index = this.getRandomIndex();
            this.nums.splice(index, 0, this.next);
            this.next++;
        },
        delNumber() {
            var index = this.getRandomIndex();
            this.nums.splice(index, 1);
        },
        shuffle() {
            this.nums.sort(() => Math.random() - 0.5);
        },
    },
};
</script>

<style>
#app {
    width: 500px;
    margin: 0 auto;
}
.nums-enter,
.nums-leave-to {
    opacity: 0;
    transform: translateX(100px);
}
.nums-enter-active,
.nums-leave-active,
/* 元素移动时起作用 */
.nums-move {
    transition: 0.5s;
}

.nums-leave-active {
    position: absolute; /* 删除的时候，需要通过改变定位来让 move 样式起作用。因此元素真正删除的时候，move样式类已经被移除了 */
}
</style>

代办事项效果

<template>
    <div class="container">
        <input
            type="text"
            @keypress.enter="addTodo"
            v-model="newTodoContent"
            class="todo-content"
            placeholder="input todo"
        />
        <button class="shuffle" @click="shuffle">随机排序</button>
        <transition-group tag="ul" name="todo" class="todo-container">
            <li v-for="item in todos" :key="item.id" class="todo">
                <span>{{ item.content }}</span>
                <button @click="finishTodo(item)">完成</button>
            </li>
        </transition-group>
    </div>
</template>

<script>
function randomId() {
    return Math.random().toString(16).substr(2, 5);
}

export default {
    data() {
        return {
            todos: [
                { id: randomId(), content: "完成「vue过渡和动画的」的学习" },
                { id: randomId(), content: "看一部电影" },
                { id: randomId(), content: "学一首新歌" },
            ],
            newTodoContent: "",
        };
    },
    methods: {
        addTodo() {
            if (!this.newTodoContent) {
                return;
            }
            this.todos.unshift({
                id: randomId(),
                content: this.newTodoContent,
            });
            this.newTodoContent = "";
        },
        finishTodo(item) {
            this.todos = this.todos.filter((it) => it !== item);
        },
        shuffle() {
            this.todos.sort(() => Math.random() - 0.5);
        },
    },
};
</script>

<style scoped>
.container {
    width: 600px;
    margin: 1em auto;

    padding: 1.5em;
    border-radius: 5px;
}
.shuffle {
    margin: 1em 0;
}
.todo-content {
    box-sizing: border-box;
    width: 100%;
    height: 50px;
    border-radius: 5px;
    outline: none;
    font-size: 1.3em;
    padding: 0 1em;
    border: 1px solid #ccc;
}
.todo-container {
    list-style: none;
    padding: 0;
    margin: 1em 0;
}
.todo {
    padding: 0.5em 0;
    border-bottom: 1px solid #ccc;
    display: flex;
    justify-content: space-between;
    margin-bottom: 1em;
}

.todo-enter {
    opacity: 0;
    transform: translateX(-100%);
}
.todo-enter-active,
.todo-leave-active,
.todo-move {
    transition: 0.5s;
}
.todo-leave-to {
    opacity: 0;
    transform: translateX(100%);
}
.todo-leave-active {
    position: absolute;
}
</style>

v-move类的实现原理（Flip）

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <ul>
            <li>title 1</li>
            <li>title 2</li>
        </ul>
        <button>交换</button>

        <script>
            var btn = document.querySelector("button");

            // 当浏览器下一次渲染之后，调用回调
            function raf(callback) {
                requestAnimationFrame(() => {
                    requestAnimationFrame(callback);
                });
            }

            function getY(dom) {
                return dom.getBoundingClientRect().top;
            }

            function applyTransition(dom, initY) {
                var curY = getY(dom); //记录变化后的位置
                var dis = initY - curY; //计算位置的差值
                dom.style.transform = `translateY(${dis}px)`;
                // 渲染之后
                raf(() => {
                    dom.style.transition = ".5s";
                    dom.style.transform = "none";
                    dom.addEventListener(
                        "transitionend",
                        () => {
                            dom.style.transition = "none";
                        },
                        {
                            once: true,
                        }
                    );
                });
            }

            btn.onclick = function () {
                var ul = document.querySelector("ul");
                var li1 = document.querySelector("ul li:nth-child(1)");
                var li1Y = getY(li1); // 拿到li1的初始位置
                var li2 = document.querySelector("ul li:nth-child(2)");
                var li2Y = getY(li2); // 拿到li2的初始位置
                ul.insertBefore(li2, li1); // 没有任何过渡效果的变化

                applyTransition(li1, li1Y);
                applyTransition(li2, li2Y);
            };
        </script>
    </body>
</html>
最近更新：:
Contributors: AK