A detailed guide to custom directives in Vue

//Will instantiate a command, but this command has no parameter `v-xxx`
 
// -- Pass the value to the instruction `v-xxx="value"`  
 
// -- Pass the string into the directive, such as `v-html="'<p>Content</p>'"`
`v-xxx="'string'"` 
 
// -- pass parameters (`arg`), such as `v-bind:class="className"`
`v-xxx:arg="value"` 
 
// -- Use modifiers (`modifier`)
`v-xxx:arg.modifier="value"` 

// Register a global custom directive `v-focus`
Vue.directive('focus', {
  // When the bound element is inserted into the DOM...
  inserted: function (el) {
    // Focus element el.focus() // A small function that automatically focuses the input box after the page is loaded}
})

directives: {
  focus:
    // Definition of instruction inserted: function (el) {
      el.focus() // A small function that automatically focuses the input box after the page is loaded}
  }
}

<input v-focus />

<div v-demo="{ color: 'white', text: 'hello!' }"></div>
<script>
    Vue.directive('demo', function (el, binding) {
    console.log(binding.value.color) // "white"
    console.log(binding.value.text) // "hello!"
    })
</script>

// 1. Set v-throttle custom directive Vue.directive('throttle', {
  bind: (el, binding) => {
    let throttleTime = binding.value; // Anti-shake timeif (!throttleTime) { // If the user does not set the anti-shake time, the default is 2s
      throttleTime = 2000;
    }
    let cbFun;
    el.addEventListener('click', event => {
      if (!cbFun) { // First execution cbFun = setTimeout(() => {
          cbFun = null;
        }, throttleTime);
      } else {
        event && event.stopImmediatePropagation();
      }
    }, true);
  },
});
// 2. Set v-throttle custom instructions for the button tag <button @click="sayHello" v-throttle>Submit</button>

const LazyLoad = {
    // install method install(Vue,options){
       // Loading image instead of image let defaultSrc = options.default;
        Vue.directive('lazy',{
            bind(el,binding){
                LazyLoad.init(el,binding.value,defaultSrc);
            },
            inserted(el){
                // Compatibility processing if('InterpObserver' in window){
                    LazyLoad.observe(el);
                }else{
                    LazyLoad.listenerScroll(el);
                }
                
            },
        })
    },
    // Initialization init(el,val,def){
        // src stores the real src
        el.setAttribute('src',val);
        // Set src to loading image el.setAttribute('src',def);
    },
    // Use InterpObserver to monitor el
    observe(el){
        let io = new InterpObserver(entries => {
            let realSrc = el.dataset.src;
            if (entries[0].isIntersecting) {
                if(realSrc){
                    el.src = realSrc;
                    el.removeAttribute('src');
                }
            }
        });
        io.observe(el);
    },
    // Listen for scroll events listenerScroll(el){
        let handler = LazyLoad.throttle(LazyLoad.load,300);
        LazyLoad.load(el);
        window.addEventListener('scroll',() => {
            handler(el);
        });
    },
    // Load the real image load(el){
        let windowHeight = document.documentElement.clientHeight
        let elTop = el.getBoundingClientRect().top;
        let elBtm = el.getBoundingClientRect().bottom;
        let realSrc = el.dataset.src;
        if(elTop - windowHeight<0&&elBtm > 0){
            if(realSrc){
                el.src = realSrc;
                el.removeAttribute('src');
            }
        }
    },
    // throttle(fn,delay){
        let timer; 
        let prevTime;
        return function(...args){
            let currTime = Date.now();
            let context = this;
            if(!prevTime) prevTime = currTime;
            clearTimeout(timer);
            
            if (currTime - prevTime > delay) {
                prevTime = currTime;
                fn.apply(context,args);
                clearTimeout(timer);
                return;
            }
 
            timer = setTimeout(function(){
                prevTime = Date.now();
                timer = null;
                fn.apply(context,args);
            },delay);
        }
    }
 
}
export default LazyLoad;

import { Message } from 'ant-design-vue';
 
const vCopy = { //
  /*
    bind hook function, called when binding for the first time, can be used to do initialization settings el: the DOM object to be acted on value: the value passed to the instruction, that is, the value we want to copy*/
  bind(el, { value }) {
    el.$value = value; // Use a global property to store the passed value, because this value will be used in other hook functions el.handler = () => {
      if (!el.$value) {
      // When the value is empty, give a prompt. The prompt I use here is the prompt of ant-design-vue. You can use it at will. Message.warning('No copy content');
        return;
      }
      // Dynamically create textarea tag const textarea = document.createElement('textarea');
      // Set the textarea to readonly to prevent the keyboard from automatically appearing on iOS, and move the textarea out of the visible area textarea.readOnly = 'readonly';
      textarea.style.position = 'absolute';
      textarea.style.left = '-9999px';
      // Assign the value to be copied to the value attribute of the textarea tag textarea.value = el.$value;
      //Insert textarea into body document.body.appendChild(textarea);
      // Select the value and copy textarea.select();
      // textarea.setSelectionRange(0, textarea.value.length);
      const result = document.execCommand('Copy');
      if (result) {
        Message.success('Copy successful');
      }
      document.body.removeChild(textarea);
    };
    // Bind click event, which is the so-called one-click copy el.addEventListener('click', el.handler);
  },
  // When the incoming value is updated, trigger componentUpdated(el, { value }) {
    el.$value = value;
  },
  // When the instruction is unbound from the element, remove the event binding unbind(el) {
    el.removeEventListener('click', el.handler);
  },
};
 
export default vCopy;

<div ref="a" id="bg" v-drag></div>

  directives: {
    drag: {
      bind() {},
      inserted(el) {
        el.onmousedown = (e) => {
          let x = e.clientX - el.offsetLeft;
          let y = e.clientY - el.offsetTop;
          document.onmousemove = (e) => {
            let xx = e.clientX - x + "px";
            let yy = e.clientY - y + "px";
            el.style.left = xx;
            el.style.top = yy;
          };
          el.onmouseup = (e) => {
            document.onmousemove = null;
          };
        };
      },
    },
  },