Skip to main content

How to customize directives in Vue?

 Vue officially provides some commonly used instructions v-text, v-html, v-model, v-if, v-show, etc. In addition, Vue also allows developers to customize related instructions. It is divided into private custom directives and global custom directives. The difference between them is: in each vue component, private custom directives can be declared under the directives node, and private custom directives only take effect in this component; globally shared custom directives Defining a directive needs to be declared via Vue.directive().

Here's a practical example:

 <div id="app">
        <input type="text" v-bind:value="n">
        <br>
        focus:<input type="text" v-my-focus:value="n">
        N:<p v-text="n"></p>
        N:<p v-add="n"></p>
        <input type="text" v-add:value="n">
        <input type="text" v-add:value="n">
        <button @click="n++">click</button>
        <p>{{a}}</p>
    </div>

    <script>
     Vue.config.productionTip=false;
     //
     Vue.directive("my-focus", function(element,binding){
        element.focus();
    })
        var vm = new Vue({
            el: '#app',
            data: {
                n:10,
                a:undefined
            },
            methods: {},
            directives:{
                add(element,binding){
                    console.log(this);
                    console.log(element,binding);
                    // element.innerText=binding.value+100;
                    element.value=binding.value;
                }
                /* add:{
                    bind(element,binding){
                        console.log(this);
                    console.log(element,binding);
                    element.innerText=binding.value+100;
                    },
                    inserted(element,binding){
                        console.log(this);
                    console.log(element,binding);
                    element.innerText=binding.value+100;
                    },
                    update(element,binding){
                        console.log(this);
                    console.log(element,binding);
                    element.innerText=binding.value+100;
                    }
                } */
            }
        });
    </script>
Summary: 

  • bind: will only be called once, which means that it will be called when the instruction is bound to the element for the first time;
  • update: When the page data is updated, this function will be triggered; 
  • inserted: Called when the element where the instruction is located is inserted into the page.

Labels:

Comments

Post a Comment

Popular posts from this blog

What is the difference between the box-size property content-box and border-box in the css box model?

 The box model is a very important concept in CSS layout, it includes content area, padding, border, and margin. Box models can be divided into two types: standard box models and IE box models. The box model, as the name suggests, is used to hold things, and the things it holds are the content of HTML elements. In other words, every visible HTML element is a box.
Post a Comment
Read more

Js uses recursive way to traverse the dom tree to dynamically create element nodes

 What is a dom tree? In short, DOM is the Document Object Model, which provides a structured representation for documents and defines how to access the document structure through scripts. DOM is composed of nodes. After the HTML is loaded, the rendering engine will generate a DOM tree in memory based on the HTML document. This article uses a small case to traverse the dom tree recursively. The core of the method is to determine whether the incoming data is an array, and then traverse the root node. Note that there must be an end condition when using recursion.
Post a Comment
Read more