vue ---> filter, calculation method, the observed attribute

Filter Properties: filters:

<div id = "app">
    {{num}}<br>
    {{num | toInt}}<br>
    {{num | toFloor}}<br>
    {{num | toCeil}}<br>
</div>
<script>
    let vm = new Vue({
        el: '#app',
        data:{
            num:'3.45',
        },
        // 过滤器
        filters:{
            toInt(value){
                return parseInt(value);
            },
            toFloor(val) {
                return Math.floor(val);
            },
            toCeil(val) {
                return Math.ceil(val);
            }
        }
    })
</script>

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Calculation of property: computed

<div id = "app">
    {{num1}} + {{num2}} = {{sum}} <br>
    {{num1}} - {{num2}} = {{subt}}
</div>
<script>
    let vm = new Vue({
        el:'#app',
        data:{
            num1:3,
            num2:2,
        },
        // 计算属性
        computed:{
            sum(){
                return this.num1+ this.num2;
            },
            subt(){
                return this.num1- this.num2;
            }
        }
    });
</script>

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Method properties: methods
observe the changes: watch

<div id ='app'>
    <p> a: {{a }}</p>
    <button v-on:click="plus">+1</button>
    <button v-on:click="to0">归0</button>
</div>
<script>
    let vm = new Vue({
        el:'#app',
        data:{
            a: 0
        },
        methods:{
            plus():{
                return this.a++;
            },
            to0():{
                return this.a = 0;
            }
        },
        watch:{
            a(){
                alert('变化了!!!');
            }
        }
    });
</script>
// 注:点击+1按钮时,直接执行plus函数.
// 使用watch观察a的值是否发生变化

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Reference https://mp.weixin.qq.com/s?__biz=MzA3MDg1NzQyNA==&mid=2649654423&idx=1&sn=3371a68990ba2d9c957f5c5daba947cb&chksm=872c4328b05bca3ed82a143ea4fd622469cfb3629bb3e0a167602acbfe6a7f799e7e7d44bbbd&scene=21#wechat_redirect

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Origin blog.csdn.net/piano9425/article/details/91986920