import Pagination from '@/components/Pagination'   // 組件路徑
Vue.component(Pagination.name,Pagination)   

<template>
    <Pagination 
		:pageNo="this.pageNo"
        :pageSize="this.pageSize"
        :total="93"
        :continues="5"
        @getPageNo="getPageNo"
/>
</template>

<script>
    export default {
        name: "index",
        data(){
			return{
			pageNo:1,
			pageSize:4,
			}	
		},
		methods:{
			getPageNo(pageNo){
			this.pageNo=pageNo
			}
		}
   
    }
</script>

<template>
    <div class="pagination">
        <!-- 上 -->
        <button :disabled="pageNo == 1" @click="getPageNo(pageNo - 1)">
            上一頁
        </button>
        <button
                v-if="startNumAndEndNum.start > 1"
                @click="getPageNo(1)"
                :class="{ active: pageNo == 1 }"
        >1
        </button>
        <button
                v-if="startNumAndEndNum.start > 2"
                @click="getPageNo(pageNo - continues)"
        >···
        </button>
        <!-- 中間部分 -->
        <button
                v-for="(page, index) in generateMiddlePage"
                :key="index"
                @click="getPageNo(page)"
                :class="{ active: pageNo == page }">
            {{ page }}
        </button>

        <!-- 下 -->
        <button
                v-if="startNumAndEndNum.end < totalPage - 1"
                @click="getPageNo(pageNo +continues)"
        >···
        </button>
        <button
                v-if="startNumAndEndNum.end < totalPage"
                @click="getPageNo(totalPage)"
                :class="{active:pageNo==totalPage}">
            {{ totalPage }}
        </button>

        <button
                :disabled="pageNo == totalPage"
                @click="getPageNo(pageNo + 1)">
            下一頁
        </button>

        <button style="margin-left: 30px">共 {{ total }} 條</button>
    </div>
</template>

<script>

    export default {
        name: "Pagination",
        props: ["pageNo", "pageSize", "total", "continues"],
        computed: {
            //計(jì)算出總頁數(shù)
            totalPage() {
			//向上取整
                return Math.ceil(this.total / this.pageSize);
            },
  			//計(jì)算出頁碼的起始和結(jié)束數(shù)字
            startNumAndEndNum() {
                const {continues, pageNo, totalPage} = this;
				//先定義兩個(gè)變量存儲(chǔ)起始數(shù)字與結(jié)束數(shù)字
                let start = 0,
                    end = 0;

                if (continues > totalPage) {
                    start = 1;
                    end = totalPage;
                } else {
					//起始數(shù)字
                    start = pageNo - parseInt(continues / 2);
					//結(jié)束數(shù)字
                    end = pageNo + parseInt(continues / 2);
                    
                    if (start < 1) {
                        start = 1;
                        end = continues;
                    }
                    
                    if (end > totalPage) {
                        end = totalPage;
                        start = totalPage - continues + 1;
                    }
                }
                return {start, end};
            },
            //過濾掉小于起始頁的頁碼
            generateMiddlePage() {
                let arr = [];
                //避免頁面中同時(shí)使用 v-for和v-if 
                for (let i = 0; i <= this.startNumAndEndNum.end; i++) {
                    arr.push(i)
                }
                let temp = arr.filter(item => {
                    return item >= this.startNumAndEndNum.start
                })
                return temp

            }
        }，
        
        methods: {
            getPageNo(val) {
            	//自定義事件子頁面向父頁面?zhèn)鲄?，?jì)算屬性值
                this.$emit('getPageNo', val)
            },

        }
    };
</script>

<style lang="less" scoped>
    .pagination {
        text-align: center;

        button {
            margin: 0 5px;
            background-color: #f4f4f5;
            color: #606266;
            outline: none;
            border-radius: 2px;
            padding: 0 4px;
            vertical-align: top;
            display: inline-block;
            font-size: 13px;
            min-width: 35.5px;
            height: 28px;
            line-height: 28px;
            cursor: pointer;
            box-sizing: border-box;
            text-align: center;
            border: 0;

            &[disabled] {
                color: #c0c4cc;
                cursor: not-allowed;
            }

            &.active {
                cursor: not-allowed;
                background-color: #409eff;
                color: #fff;
            }
        }
    }

    .active {
        background: skyblue;
    }
</style>