Uniapp obtains the date implementation of the beginning and end of the previous month and the next month

<template>
	<view>
		<button type="" @click="last()"> Last month </button>
		<button type="" @click="next()"> Next month </button>
		<view class="" >
			{
    {
    startDate}}
		</view>
		<view class="">
			{
    {
    endDate}}
		</view>
		
	</view>
</template>

<script>
	export default {
    
		data() {
    
			return {
    
				nowDate:"",
				fullYear:"",
				month:"",
				endOfMonth:"",
				endDate:"",
				startDate:""
			}
		},
		onReady() {
    
			this.nowDate = new Date();
			this.fullYear =  this.nowDate.getFullYear();
			this.month = this.nowDate.getMonth() + 1; // getMonth  Method returns  0-11, representative 1-12 month 
			this.endOfMonth = new Date(this.fullYear, this.month, 0).getDate(); //  Get the last day of the month 
			this.endDate = this.getFullDate(this.nowDate.setDate(this.endOfMonth));// The last day of the month 
			this.startDate = this.getFullDate(this.nowDate.setDate(1));// The first day of the month 
			
		},
		methods: {
    
			getFullDate(targetDate) {
    
			  var D, y, m, d;
			  if (targetDate) {
    
			      D = new Date(targetDate);
			      y = D.getFullYear();
			      m = D.getMonth() + 1;
			      d = D.getDate();
			  } else {
    
			      y = fullYear;
			      m = month;
			      d = date;
			  }
			  m = m > 9 ? m : '0' + m;
			  d = d > 9 ? d : '0' + d;
			  return y + '-' + m + '-' + d;
			},
			last(){
    
				this.nowDate.setMonth(this.nowDate.getMonth()-1);
				this.startDate = this.nowDate.getFullYear() + "-" + (this.nowDate.getMonth()+1) + "-" + this.nowDate.getDate()
				this.endDate =this.getFullDate(new Date(this.nowDate.getFullYear(), this.nowDate.getMonth() + 1, 0)) 
				
			},
			next(){
    
				this.nowDate.setMonth(this.nowDate.getMonth()+1);
				this.startDate = this.nowDate.getFullYear() + "-" + (this.nowDate.getMonth()+1) + "-" + this.nowDate.getDate()
				this.endDate =this.getFullDate(new Date(this.nowDate.getFullYear(), this.nowDate.getMonth() + 1, 0))
			}
		},
		
	}
</script>

<style>

</style>