<el-date-picker v-model="form.regDateBeg" type="date" value-format="yyyy-MM-dd" placeholder="开始日期"></el-date-picker>

var faiSearchObj = new Vue({
	el: '.fai-payRecord-search',
	data: {
		form: {
			regDateBeg: dateFormatter(new Date(), false),//这个日期参数，这里做了修改
			...(其他无关参数，省略)
		}
	},
	methods: {
		onSubmit() {
			console.log(this.form.regDateBeg);  
		}
    }
});

function dateFormatter(str){//默认返回yyyy-MM-dd HH-mm-ss
	var hasTime = arguments[1] != false ? true : false;//可传第二个参数false，返回yyyy-MM-dd
	var d = new Date(str);
	var year = d.getFullYear();
	var month = (d.getMonth()+1)<10 ? '0'+(d.getMonth()+1) : (d.getMonth()+1);
	var day = d.getDate()<10 ? '0'+d.getDate() : d.getDate();
	var hour = d.getHours()<10 ? '0'+d.getHours() : d.getHours();
	var minute = d.getMinutes()<10 ? '0'+d.getMinutes() : d.getMinutes();
	var second = d.getSeconds()<10 ? '0'+d.getSeconds() : d.getSeconds();
	if(hasTime){
		return [year, month, day].join('-') + " " + [hour, minute, second].join(':');
	}else{
		return [year, month, day].join('-');
	}
}