vue 自定义指令的使用案例

参考资料：

　　v-loading，是 element-ui 组件库中的一个用于数据加载过程中的过渡动画指令，项目中也很少需要自己去写自定以指令。碰巧这段时间自己练习了编写组件，完成看看能不能实现一个自定义的这样一个指令。话不多说，上代码：

<div class="table" v-loadAnimation="loading">
    ...
</div>
 
<script>
export default {
    data() {
        return {
            ...
        }
    },
    directives: {
        loadAnimation: {
            bind: (el, binding) => {
                // console.log('bind', el, binding)
                // 遮罩层
                const modal = document.createElement('div');
                modal.className = 'modal-loading';
                // 遮罩层动画
                const animation = document.createElement('div');
                animation.className = 'modal-loading-animation';
                modal.appendChild(animation);
                // 自定义的 loadingElement 属性/其他, 下面钩子函数可以使用;
                el.loadingElement = modal;
 
                const curStyle = window.getComputedStyle(el);
                const position = curStyle.position;
                 
                if (position === 'absolute' || position === 'relative') {
                    el.style.position = position;
                } else {
                    el.style.position = 'relative';
                }
 
                if (binding.value) {
                    el.appendChild(modal)
                }
            },
            update: (el, binding) => {
                // console.log('update', el, binding)
                if (binding.value) {
                    if (el.loadingElement.parentNode === null) {
                        el.appendChild(el.loadingElement);
                    }
                } else {
                    if (el === el.loadingElement.parentNode) {
                        el.removeChild(el.loadingElement);
                    }
                }
            },
            unbind: (el) => {
                if (el.loadingElement.parentNode === el) {
                    el.removeChild(el.loadingElement);
                }
                el.loadingElement = null;
            }
        }
    },
    methods: {
        ...
    }
}
</script>
 
<style> 
/* for loading animation */
.modal-loading {
    width: 100%;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    z-index: 100;
    background-color: rgba(255, 255, 255, 0.95);
    overflow: hidden;
}
.modal-loading .modal-loading-animation {
    width: 30px;
    height: 30px;
    border-radius: 50%;
    border: 4px solid #1a7dff;
    border-left-color: transparent;
    animation: modal-loading-rotate 1s linear infinite;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}
@keyframes modal-loading-rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}
</style>