练习1:在输入框聚焦时,增加对键盘上下键按键的支持,相当于加1和减1
练习2:增加一个控制步伐的prop-step,比如设置为10,点击加号按钮,一次增加10
思路:
// 考虑到子模板的复用性,即在父模板中复用如下:
<input-number v-model="value" :max="10" :min="0" :step="3"></input-number>
// v-model将input中的值和父模板data下面value的值绑定到一起
// 可以通过:max,:min限制输入框的最大最小值
// 通过:step来设置子模版点击加号时的步伐(即,一次加多少)
几个补充:
@focus: 用于绑定input的聚焦事件
@blur: 用于绑定input的失去焦点事件
@keyup.down: 绑定键盘的向下键
@keyup.up: 绑定键盘的向上键
总体代码如下:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body><div id="app"><input-number v-model="value" :max="10" :min="0" :step="3"></input-number></div><script src="https://unpkg.com/vue@2.6.10/dist/vue.min.js"></script>
<script>Vue.component('input-number',{template:'\<div class="input-number">\<input type="text" :value="currentValue" @change="handleChange" @focus="handleFocus" @blur="handleBlur" @keyup.down="handleArrowDown" @keyup.up="handleArrowUp">\<button @click="handleDown" :disabled="currentValue <= min">-</button>\<button @click="handleUp" :disabled="currentValue >= max">+</button>\</div>',props:{max:{type:Number,default:Infinity},min:{type:Number,default:-Infinity},value:{type:Number,default:0},step:{type:Number,default:1}},data:function (){return {currentValue: this.value,isFocus:false}},methods:{handleUp:function() {this.currentValue += this.step;},handleDown:function() {this.currentValue -= this.step;},isValueNumber:function(value) {return (/(^-?[0-9]+\.{1}\d+$)|(^-?[1-9][0-9]*$)|(^-?0{1}$)/).test(value + '');},handleChange:function(event){let val = event.target.value.trim();let max = this.max;let min = this.min;if(this.isValueNumber(val)){val = Number(val);this.currentValue = val;if(val > max){this.currentValue = max;} else if (val < min) {this.currentValue = min;}} else {event.target.value = this.currentValue;}},updateValue:function(val){if(val > this.max) val = this.max;if(val < this.min) val = this.min;this.currentValue = val;},handleFocus:function(){this.isFocus = true},handleBlur:function(){this.isFocus = false},handleArrowDown:function(){if(this.isFocus){this.handleDown();}},handleArrowUp:function(){if(this.isFocus){this.handleUp();}}},watch:{currentValue: function(val) {this.$emit('input',val);},value: function(val){this.updateValue(val);}}})const app = new Vue({el:'#app',data:{value:5}})
</script></body>
</html>
参考《Vue.js实战》P98~P106
)
