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/[email protected]/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