Skip to main content

The use of v-for directive in Vue

In Vue, a v-for loop is used to get dynamic data, thus creating a dom tree, such as the very common ul>li list. When I need to traverse an array or enumerate an object and display it in a loop, I often use the list rendering instruction v-for. It needs to be used in combination with in or of, as follows. When Vue renders elements, for the sake of efficiency, it will reuse existing elements as much as possible instead of re-rendering. If you don't want this, you can use the key attribute provided by Vue, which allows you to decide whether to reuse elements. Key The value must be unique.

Look directly at the sample code as follows:

   <div id="app">
        <h2>v-for:</h2>
Please enter the value you want to filter(name or age):<input type="text" v-model="inputVal">
        <ul>
            <li v-for="(value,index) of filterPerson">{{value.id}}-{{value.name}}-{{value.age}}</li>
        </ul>
    </div>
    <script>
     Vue.config.productionTip=false;
         var vm = new Vue({
            el: '#app',
            data: {
                inputVal:'',
                num:100,
                person:[
                    {id:1001,name:"aaa",age:18},
                    {id:1002,name:"bbb",age:19},
                    {id:1003,name:"ccc",age:20}
                ],
                filterPerson:[]
            },
            methods: {  
            },
            watch:{
                inputVal:{
               immediate:true,
               handler(value){
                this.filterPerson=this.person.filter((item)=>{
                    return item.name.indexOf(value)!==-1||item.age.toString()===value;
                })
               }
            }
        }
        });
     /*     var vm = new Vue({
            el: '#app',
            data: {
                inputVal:'',
                num:100,
                person:[
                    {id:1001,name:"aaa",age:18},
                    {id:1002,name:"bbb",age:19},
                    {id:1003,name:"ccc",age:20}
                ],  
            },
            methods: {  
            },
            computed:{
                filterPerson(){
                  let afterval=  this.person.filter((item)=>{
        return item.name.indexOf(this.inputVal)!==-1||item.age.toString()===this.inputVal;
                    })
                    return afterval;
                }
            }
        }); */
    </script>

Comments

Popular posts from this blog

What is the difference between width property 100% and auto in css?

 width:auto: The default width value of block-level elements. When set to this value, the browser will automatically select an appropriate width value to adapt to the width of the parent element. When the width is set to 100%, the width of the child element box The value is equal to the parent's content, and as the parent's content automatically changes, after adding the padding and margin of the child element, its width remains unchanged, which is the difference from setting it to auto. But we most often use width:auto, because it is more flexible, width:100% is used less, because when adding padding or margin, this method is easy to make it exceed the parent box and destroy the original layout.

Access to XMLHttpRequest at 'http://localhost:8080/xxx' from origin 'http://localhost:8080' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

 Due to browser same-origin policy restrictions. The Same Origin Policy is a convention. This is the main and essential security feature of the browser. Without the same-origin policy, normal browser functionality may be affected. The web is built on the same-origin policy, and browsers are just one implementation of the same-origin policy. The Same Origin Policy prevents JavaScript scripts from one domain from interacting with content from another domain. The so-called same origin (that is, the same domain) means that two pages have the same protocol, host and port.