SOURCE

<div id="app">
    <button @click="sendCode" :disabled="isSend">{{sendTip}}</button>
</div>
<script>
    var vm = new Vue({
        el:"#app",
        data(){
            return {
                sendTip:'获取验证码',
                isSend:false
            }
        },
        methods:{
            sendCode(){
                this.time = 20;
                this.timer();
            },
            timer(){
                if(this.time>0){
                    this.isSend = true; //按钮不可点击
                    this.time--;
                    this.sendTip = this.time + 's后重新获取';
                    setTimeout(this.timer,1000) //自执行本身，每隔一秒调用一次
                }else{
                    this.time = 0;
                    this.sendTip = '获取验证码';
                    this.isSend = false //按钮可以点击
                }
            }
        }
    })
</script>