vue元件化

原理：檢查是否相容position: sticky ，若相容就使用，若不相容則在watch監聽高度(若高度是變化的)或者在mounted中直接呼叫(高度不變)

 1 <template>
 2     <div class="header_sticky">
 3         <slot></slot>
 4     </div>
 5 </template>
 6 <script>
 7 export default {
 8     name: 'stickyHeader',
 
 9     computed: {
10         randomId: function(){
11             return 'randomId_' + Number(Math.random().toString().substr(3,3) + Date.now()).toString(36);
12         },
13         targetElement_: function() {
14             return this.$el
15         }
16     },
17     methods: {
18         // |-> css: 用於替換的css樣式; (一般用預設的)
 

19         sticky_(css='sticky_') {
20             if (CSS.supports('position', 'sticky') || CSS.supports('position', '-webkit-sticky')) {
21                 console.log('>>>>>>>>> sticky is supported')
22             } else {
23                 let newNodeTop;
24                 let header = this
 
.targetElement_;
25                 if(document.getElementById(this.randomId)) {
26                     newNodeTop = document.getElementById(this.randomId);
27                 }else{
28                     newNodeTop = document.createElement("div");
29                     newNodeTop.id = this.randomId;
30                     header.parentNode.insertBefore(newNodeTop, header);
31                     header.classList.add(css);
32                 }
33 
34                 setTimeout(() => {
35                     let height = header.offsetHeight + 1; //高度 + 1 以防有小數點
36                     newNodeTop.style.height = height + 'px';
37                 }, 0)
38             }
39         },
40     }
41 }
42 </script>

/***********      ！要用非同步獲取高度       */

css

 1 .header_sticky {
 2     width: 100%;
 3     position: sticky;
 4     position: -webkit-sticky;
 5     top: 0;
 6     z-index: 100;
 7     transition: height 1s;
 8     -moz-transition: height 1s;
 9     -webkit-transition: height 1s;
10     -o-transition: height 1s;
11 }
12 
13 .sticky_ {
14     width: 100%;
15     position: fixed;
16     position: -webkit-fixed;
17     top: 0;
18     z-index: 100;
19 }

在watch中監聽高度變化

1 watch: {
2             oldToNew(newVal, oldVal) {
3                 if(newVal.length !== oldVal.length) {
4                     this.$refs.sticky_.sticky_()
5                 }
6             }
7         }

在mounted中獲取高度變化

this.$refs.sticky_.sticky_()

<使用>

html

<sticky-header ref="sticky_">
    <!-- contents -->
</sticky-header>