Vue에서는 기본 핵심 지시문(v-model 및 v-show) 외에도 사용자 지정 지시문 등록도 허용합니다. 이 기사에서는 네 가지 실용적인 vue 사용자 정의 지침을 공유하겠습니다. 이것이 도움이 되기를 바랍니다.
1, v-dragv-drag
需求：鼠标拖动元素
思路：
代码：
Vue.directive('drag', {
inserted(el) {
let header = el.querySelector('.dialog_header')
header.style.cssText += ';cursor:move;'
header.onmousedown = function (e) {
//获取当前可视区域宽、高
let clientWidth = document.documentElement.clientWidth
let clientHeight = document.documentElement.clientHeight
//获取自身宽高
let elWidth = el.getBoundingClientRect().width
let elHeight = el.getBoundingClientRect().height
//获取当前距离可视区域的top、left
let elTop = el.getBoundingClientRect().top
let elLeft = el.getBoundingClientRect().left
//获取点击时候的坐标
let startX = e.pageX
let startY = e.pageY
document.onmousemove = function (e) {
//元素偏移量 = 鼠标滑动后的坐标 - 鼠标初始点击元素时的坐标 + 初始点击时元素距离可视区域的top、left
let moveX = e.pageX - startX + elLeft
let moveY = e.pageY - startY + elTop
//将可视区域作为边界，限制在可视区域里面拖拽
if ((moveX + elWidth) > clientWidth || moveX < 0 || (moveY + elHeight) > clientHeight || moveY < 0) {
return
}
el.style.cssText += 'top:' + moveY + 'px;left:' + moveX + 'px;'
}
document.onmouseup = function () {
document.onmousemove = null
document.onmouseup = null
}
}
}
})2、v-wordlimit
需求：后台字段限制了长度，并且区分中英文，中文两个字节，英文一个字节；所以输入框需要限制输入的字数并且区分字节数，且需回显已输入的字数。
思路：
代码：
Vue.directive('wordlimit',{
bind(el,binding){
console.log('bind');
let { value } = binding
Vue.nextTick(() =>{
//找到输入框是textarea框还是input框
let current = 0
let arr = Array.prototype.slice.call(el.children)
for (let i = 0; i < arr.length; i++) {
if(arr[i].tagName=='TEXTAREA' || arr[i].tagName=='INPUT'){
current = i
}
}
//更新当前输入框的字节数
el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,'**').length +'/'+value//eslint-disable-line
})
},
update(el,binding){
console.log('update');
let { value } = binding
Vue.nextTick(() =>{
//找到输入框是textarea框还是input框
let current = 0
let arr = Array.prototype.slice.call(el.children)
for (let i = 0; i < arr.length; i++) {
if(arr[i].tagName=='TEXTAREA' || arr[i].tagName=='INPUT'){
current = i
}
}
//更新当前输入框的字节数
el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,'**').length +'/'+value//eslint-disable-line
})
},
inserted(el,binding){
console.log('inserted');
let { value } = binding
//找到输入框是textarea框还是input框
let current = 0
let arr = Array.prototype.slice.call(el.children)
for (let i = 0; i < arr.length; i++) {
if(arr[i].tagName=='TEXTAREA' || arr[i].tagName=='INPUT'){
current = i
}
}
//创建包裹字数限制的元素，并定位布局在textarea和input框上
let div = document.createElement('div')
if(el.children[current].tagName=='TEXTAREA'){//是textarea，定位在右下角
div.style = 'color:#909399;position:absolute;font-size:12px;bottom:5px;right:10px;'
}else{
let styStr = ''
if(!el.classList.contains('is-disabled')){//input框不是置灰的状态则添加背景颜色
styStr = 'background:#fff;'
}
div.style = 'color:#909399;position:absolute;font-size:12px;bottom:2px;right:10px;line-height:28px;height:28px;'+styStr
}
div.innerHTML = '0/'+ value
el.appendChild(div)
el.children[current].style.paddingRight = '60px'
el.oninput = () =>{
let val = el.children[current].value
val = val.replace(/[^\x00-\xff]/g,'**') //eslint-disable-line
// 字数限制的盒子插入到el后是最后一个元素
el.children[el.children.length-1].innerHTML = val.length + '/' + value
if(val.length>value){
let cnLen = 0 //一个字节的字数
let enLen = 0 //两个字节的字数
if(val.match(/[^**]/g) && val.match(/[^**]/g).length){
enLen = val.match(/[^**]/g).length // 计算一个字节的字数
//一个字节两个字节都有的情况
if((value - val.match(/[^**]/g).length)>0){
cnLen = Math.floor((value - val.match(/[^**]/g).length)/2)
}else{
cnLen = 0
}
}else{ //全部两个字节的情况
enLen = 0
cnLen = Math.floor(value/2)
}
if(enLen>value){
enLen = value
}
//超过限定字节数则截取
el.children[current].value = el.children[current].value.substr(0,enLen+cnLen)
//更新当前输入框的字节数
el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,'**').length +'/'+value//eslint-disable-line
}
}
},
})使用：
<el-input type="textarea" rows="3" v-wordlimit="20" v-model="value"></el-input>
3、v-anthor
需求：点击某个元素（通常是标题、副标题之类的），动画滚动到对应的内容块
思路：
代码：
Vue.directive('anchor',{
inserted(el,binding){
let { value } = binding
let timer = null
el.addEventListener('click',function(){
// 当前元素距离可视区域顶部的距离
let currentTop = el.getBoundingClientRect().top
animateScroll(currentTop)
},false)
function animateScroll(currentTop){
if(timer){
clearInterval(timer)
}
let c = 9
timer = setInterval(() =>{
if(c==0){
clearInterval(timer)
}
c--
window.scrollBy(0,(currentTop-value)/10)
},16.7)
}
}
})使用：
<div class="box" v-anchor="20" style="color:red;">是的</div>
4、v-hasRole
![[웹 프런트엔드] Node.js 빠른 시작](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
